Fluorinated Derivatives of 3-Hydroxypyridin-4-Ones

ABSTRACT

Compounds of Formula I which are derivatives of 3-Hydroxypyridin-4-ones. The compounds may be used in treatment of a medical condition related to a toxic concentration of iron. The compounds may be used for preparation of a medicament for treatment of a medical condition related to a toxic concentration of iron. The medical condition related to a toxic concentration of iron may be selected from the group consisting of: cancer, pulmonary disease, progressive kidney disease and Friedreich&#39;s ataxia.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/735,718, filed Jun. 10, 2015, which is a divisional application ofU.S. patent application Ser. No. 13/382,130, now U.S. Pat. No.9,073,865, filed Jun. 21, 2012, which is the U.S. national stage of PCTApplication No. PCT/CA2010/001027, filed Jul. 5, 2010, which claimspriority from U.S. Provisional Application No. 61/222,979, filed Jul. 3,2009, the disclosures of which are each incorporated herein by referencein their entirety.

BACKGROUND

The occurrence of in vivo iron toxicity in the human body can becategorized into iron overload and non-iron overload conditions. Ironoverload conditions are common in thalassaemia patients through chronicblood transfusions and in hereditary haemochromatosis patients. Non-ironoverloaded conditions include anthracycline mediated cardiotoxicity,viral infections, neurodegenerative diseases, photo induced damage, andproliferative conditions. The potential use of iron chelators in thetreatment of a variety of diseases is reviewed in Tam et al., CurrentMedicinal Chemistry, 2003, 10, 983-995 and Hider et al., BioMetals,2007, 20, 639-654.

At present, there are several iron chelator drugs that have reached themarket. Examples of those include deferiprone (Ferriprox™), ICL670(ExJade™), dexrazoxane hydrochloride (Zinecard™) and desferrioxaminemesylate (Desferal™). However, only two of these compounds, namelydeferiprone and ICL670, are orally active for the removal of iron iniron-overloaded diseases.

SUMMARY

In designing 3-hydroxypyridin-4-one that will lead to improved brainexposure, one approach is to increase the lipophilicity of the chelatorvia the introduction of a trifluoroethyl group at the C2 or C5 or C6position of the 3-hydroxypyridin-4-one (US20080242706). This inventionis based in part on compounds with a trifluoroethyl group at the N1position, or a 2-difluoroethyl group at the C2 position of the3-hydroxypyridin-4-one skeleton. The use of low molecular weightsubstituents is also considered in the design of new bidentate3-hydroxypyridin-4-one ligands (L). A ML_(n) complex is formed uponcomplexation with a metal (M), for example FeL₃.

Amines are known to have favorable interaction with predominatelynegatively charged phospholipids head groups at the BBB (blood brainbarrier). In general, bases penetrate better into the CNS (centralnervous system) (Chapter 10, Blood Brain Barrier in Drug-LikeProperties: Concepts, Structure Design and Methods, by Edward H. Kernsand Li Di, Academic Press, Elsevier 2008). Herein, a series of aminoderivatives with trifluoroethyl at the C2 or N1 or C5 or C6 position ofthe 3-hydroxypyridin-4-one backbone are designed and synthesized.Selected examples of those compounds are2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one(Apo7041),5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one(Apo7053), and6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(Apo7021), and2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(Apo7067).

This invention is based in part on a serendipitous discovery that aminederivatives such as2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one(Apo7041) are less favorable than deferiprone in BBB penetration incassette dosing BBB studies in rats. Physicochemical studies confirmthat Apo7041 (pKa=3.51) is less basic than normal aliphatic amines.Certain selected amine derivatives of this invention are weak bases andhave pKas in the range of 3.5 to 6.0.

The weak bases of this invention are lipophilic and may also possess theability to accumulate in the acidic compartment of biological systems.In addition, the metal chelates of compounds of this invention may havea distinctive property of being stable at significantly lower pHs thanthe metal chelate of deferiprone. The compounds of this invention may beuseful in biological conditions such as treatment of cancer,inflammatory lung disorders and renal disease wherein the therapyrequires a weak base to accumulate in the acidic compartment andsequester free iron under slightly acidic conditions to form a stableferric chelate, which results in the removal of iron.

On the other hand, fluorinated derivatives of 3-hydroxypyridin-4-oneswith a basic amine with pKa>6.0 have different properties than theweakly basic amines such as Apo7041. An example of such is2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(Apo7067, pKa=6.1). Apo7067 is more lipophilic than deferiprone andreadily penetrates the BBB in cassette dosing BBB studies in rats.

Non-amino fluorinated 3-hydroxypyridin-4-ones derivatives of thisinvention are generally more lipophilic than deferiprone and canaccumulate in the brain region. Examples of those compounds are3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo6995),3-hydroxy-2-(hydroxymethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(Apo7064), 2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one(Apo7080) and2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one(Apo7078). Compounds such as Apo6995 may be useful as low molecularweight iron chelators for accumulation in the brain. One possible use isthe treatment of Friedreich's ataxia, wherein the site of iron removalor redistribution is in the brain.

In illustrative embodiments of the present invention there is provided acompound of Formula I:

wherein G¹ is H, C₁-C₄ alkyl, CH₂OH, CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H,NR¹R², or

G² is H, C₁-C₄ alkyl, cyclopropyl or (CH₂)_(n)CF₂R³; G³ is H, C₁-C₄alkyl, CH₂OH, CH₂NR¹R², CH(R⁶)CF₃, CH₂-A-OH, CH₂-A-NHR⁹ or CH₂CF₃ or

and G⁴ is H, C₁-C₄ alkyl, halo or CH(R⁸)CF₃; n is 1, 2 or 3; R¹ and R²are either (a) two independent groups or (b) together form a single ringgroup; R¹ and R², when independent groups, are independently selectedfrom the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl,and propargyl; R¹ and R², when together form a single ring group, areselected from the group consisting of: piperazinyl, N—(C₁-C₄alkyl)-substituted piperazinyl, morpholinyl, and piperidinyl; R³ is H orF; R⁴ and R⁷ are independently selected from the group consisting of: H,OH, NR¹R², imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl,2-pyridylpiperazinyl and -A-NH—R¹⁰; and when R⁴ or R⁷ is imidazolyl,1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl,N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or-A-NH—R¹⁰, a point of attachment of R⁴ or R⁷ to the CH moiety of G¹ isan N atom of R⁴ or R⁷; R⁵ is C₁-C₄ alkyl; R⁶ is H or OH; R⁸ is selectedfrom the group consisting of: NR¹R², imidazolyl, 1-2-4-triazolyl,piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl,N-phenylpiperazinyl, 2-pyridylpiperazinyl and -A-NH—R¹⁰; and when R⁸ isimidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl,N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or-A-NH—R¹⁰ a point of attachment of R⁸ to the CH moiety of G⁴ is an Natom of R⁸; R⁹ and R¹⁰ are independently H or C₁-C₄ alkyl; A is—NH—(CH₂)_(m)—CO— or an alpha amino acid residue; m is 1, 2 or 3; andprovided that: at least one of G¹, G², G³ and G⁴ comprise at least onefluorine moiety; when G¹ is CH(R⁴)CF₃ and R⁴ is H or OH, then either (i)G³ is CH₂NR¹R², CH₂-A-OH, CH₂-A-NHR⁹ or (ii) G⁴ is halo or CH(NR¹R²)CF₃;and when G³ is CH(R⁶)CF₃, then G¹ is CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H,NR¹R² or

In illustrative embodiments of the present invention, there is provideduse of a compound described herein for treatment of a medical conditionrelated to a toxic concentration of iron. The use may be for preparationof a medicament. The medical condition related to a toxic concentrationof iron may be selected from the group consisting of: cancer, pulmonarydisease, progressive kidney disease and Friedreich's ataxia.

In illustrative embodiments of the present invention, there is provideda method of medical treatment comprising administering a therapeuticallyeffective amount of a compound described herein to a subject having orsuspected of having a medical condition related to a toxic concentrationof iron. The medical condition related to a toxic concentration of ironmay be selected from the group consisting of: cancer, pulmonary disease,progressive kidney disease and Friedreich's ataxia.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of E_(1/2) zone of establisheddrugs such as deferiprone and desferroxamine B. When a ferric chelatehas an E_(1/2) value that falls below −320 mV (mV vs. NHE), the chelateis not redox active and its properties fall within the E_(1/2) zone ofestablished drugs such as deferiprone and desferroxamine B, and bodyprotein such as transferrin. Compounds of Formula I have E_(1/2) valuesthat fall within the zone between ferrioxamine B (iron chelate ofdesferrioxamine B) and Fe(deferiprone)₃. Both deferiprone and Apo7041are 3-hydroxypyridin-4-one derivatives. Deferiprone is3-hydroxy-1,2-dimethylpyridin-4(1H)-one and Apo7041 is2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one.

FIG. 2 is a diagrammatic representation of the cyclic voltammetry (CV)of the Fe chelate of three representative compounds of Formula I,Apo7041 (G²=Me, G¹=CH(NMe₂)CF₃, G⁴=H, G³=H), Apo7053 (G²=Me, G¹=Me,G⁴=CH(NMe₂)CF₃, G³=H), Apo7069 (G²=CH₂CHF₂, G¹=Me, G⁴=H, G³=H).

FIG. 3A is a diagrammatic representation of a Job's Plot of Apo 70535-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one,a compound of Formula I.

FIG. 3B is a diagrammatic representation of a Job's plot for Fe-Apo7041system with [Fe]_(total)+[Apo7041]_(total)=8×10⁻⁴ M in 0.1 M MOPS at pH7.4.

FIG. 4 is a diagrammatic representation of the Fe speciation plot of theFe: deferiprone system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and[deferiprone]=1×10⁻⁵ M.

FIG. 5 is a diagrammatic representation of the Fe speciation plot of theFe: Apo7041 system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and[Apo7041]=1×10⁻⁵ M.

FIG. 6 is a diagrammatic representation of the protonation of thechelate of Apo7041. The Fe-chelate of a weak base is a proton sink.Protonated FeL₃ species via protonation of the amine moieties FeL₃ toFeL₂ are present in acidic medium. Conversion of FeL₃ to FeL₂ occursonly at very low acidic pH.

FIG. 7 is a diagrammatic representation of the degradation of FeL₃ toFeL₂ for neutral 3-hydroxypyridin-4-ones.

FIG. 8 is a diagrammatic representation of the Apo7041 ligand. Thesteric bulk at the C2 position is designed to block phase II metabolisminvolving glucuronidation of the C3 oxygen.

FIG. 9. A diagramatic representation showing that a compound of formulaI and deferiprone suppresses the formation of the hydroxybenzoic acidwhen benzoic acid is treated with hydrogen peroxide and iron salts. They axis refers to the total concentration of 2-hydoxybenzoic acid,3-hydoxybenzoic acid, and 4-hydoxybenzoic acid formed (unit: μM).

FIG. 10 is a diagrammatic representation of the neuroprotective actionof deferiprone on MPP+ treated SV-NRA cells. MPP⁺ treatment decreasedcell viability when compared to untreated vehicle control. Treatmentwith deferiprone, an iron chelator drug resulted in about 20% increasein cell viability (p<0.05).

FIG. 11 is a diagrammatic representation showing the neuroprotectiveaction of Apo7021, a compound of formula I, on MPP+ treated SV-NRAcells.

FIG. 12 is a diagrammatic representation showing the neuroprotectiveaction of Apo7060, a compound of formula I, on MPP+ treated SV-NRAcells.

FIG. 13 is a diagrammatic representation showing the neuroprotectiveaction of Apo6995, a compound of formula I, on MPP+ treated SV-NRAcells.

DETAILED DESCRIPTION

Compounds of the present invention comprise compounds having a structureaccording to Formula I:

wherein

G¹ is H, C₁-C₄ alkyl, CH₂OH, CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H, NR¹R², or

G² is H, C₁-C₄ alkyl, cyclopropyl or (CH₂)_(n)CF₂R³;

G³ is H, C₁-C₄ alkyl, CH₂OH, CH₂NR¹R², CH(R⁶)CF₃, CH₂-A-OH, CH₂-A-NHR⁹or CH₂CF₃ or

and

G⁴ is H, C₁-C₄ alkyl, halo or CH(R⁸)CF₃;

n is 1, 2 or 3;

R¹ and R² are either (a) two independent groups or (b) together form asingle ring group;

R¹ and R², when independent groups, are independently selected from thegroup consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, andpropargyl;

R¹ and R², when together form a single ring group, are selected from thegroup consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substitutedpiperazinyl, morpholinyl, and piperidinyl;

R³ is H or F;

R⁴ and R⁷ are independently selected from the group consisting of: H,OH, NR¹R², imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl,2-pyridylpiperazinyl and -A-NH—R¹⁰; and when R⁴ or R⁷ is imidazolyl,1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl,N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or-A-NH—R¹⁰, a point of attachment of R⁴ or R⁷ to the CH moiety of G¹ isan N atom of R⁴ or R⁷;

R⁵ is C₁-C₄ alkyl;

R⁶ is H or OH;

R⁸ is selected from the group consisting of: NR¹R², imidazolyl,1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl,N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl and-A-NH—R¹⁰; and when R⁸ is imidazolyl, 1-2-4-triazolyl, piperazinyl,N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl,2-pyridylpiperazinyl or -A-NH—R¹⁰ a point of attachment of R⁸ to the CHmoiety of G⁴ is an N atom of R⁸;

R⁹ and R¹⁰ are independently H or C₁-C₄ alkyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and

provided that:

at least one of G¹, G², G³ and G⁴ comprise at least one fluorine moiety;

when G¹ is CH(R⁴)CF₃ and R⁴ is H or OH, then either (i) G³ is CH₂NR¹R²,CH₂-A-OH, CH₂-A-NHR⁹ or (ii) G⁴ is halo or CH(NR¹R²)CF₃; and

when G³ is CH(R⁶)CF₃, then G¹ is CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H, NR¹R²or

When G¹ comprises a fluorine moiety, then G¹ is selected from the groupconsisting of: CH(R⁴)CF₃, CH(R⁷)CF₂H, and

When G² comprises a fluorine moiety, then G² is (CH₂)_(n)CF₂R³.

When G³ comprises a fluorine moiety, then G³ is selected from the groupconsisting of: CH(R⁶)CF₃, CH₂CF₃ and

When G⁴ comprises a fluorine moiety, then G⁴ is CH(R⁸)CF₃.

As used throughout this document, unless otherwise made clear by thecontext, A may be —NH—(CH₂)_(m)—CO— wherein m is 1, 2, or 3 or an alphaamino acid residue. A has a point of attachment to the compound via anitrogen atom (N atom). The attachment point may be, for example, at theN-terminal of the amino acid residue. If the amino acid is lysine orornithine, it is possible that either the alpha N or epsilon N of lysineor the alpha N or delta N of ornithine can be the attachment point. Inthe A-NHR⁹ or A-NHR¹⁰ moieties, the carboxylic acid of the amino acidresidue forms an amide with the nitrogen atom of NHR⁹ or NHR¹⁰. In theA-OH moieties, the C-terminal of the amino acid residue is a carboxylicacid;

As used herein, an amino acid residue includes, but is not limited to,any of the naturally occurring alpha-, beta-, and gamma-amino carboxylicacids, including their D and L optical isomers, and the N-lower alkyl-and N-phenyl lower alkyl-derivatives of these amino acids. The aminoacid residue is bonded through a nitrogen of the amino acid. Thenaturally occurring amino acids which can be incorporated into thepresent invention include, but are not limited to, alanine (ala),arginine (arg), asparagine (asn), aspartic acid (asp), cysteine (cys),cystine, glutamic acid (glu), glutamine (gin), glycine (gly), histidine(his), isoleucine (iso), leucine (leu), lysine (lys), methionine (met),ornithine (orn), phenylalanine (phe), proline (pro), serine (ser),threonine (thr), thyroxine, tryptophan (trp), tyrosine (tyr), valine(val), beta-alanine (β-ala), and gamma-aminobutyric acid (gaba).Preferred amino acid residues include proline, leucine, phenylalanine,isoleucine, alanine, gamma-amino butyric acid, valine, glycine, andphenylglycine.

All alpha-amino acids except glycine contain at least one asymmetriccarbon atom. As a result, they are optically active, existing in eitherD or L form as a racemic mixture. Accordingly, some of the compounds ofthe present invention may be prepared in optically active form, or asracemic mixtures of the compounds claimed herein.

For example, the term A-OH wherein A is D-alanyl has the followingstructure:

The term A-NHMe wherein A is D-alanyl has the following structure

The term A-OH wherein A is —NH—(CH₂)_(m)—CO— and m is 2 has thefollowing structure:

The term A-NHMe wherein A is epsilon-lysyl has the following structure:

The term A-NHMe wherein A is alpha-lysyl has the following structure:

As used herein, the term “alkyl,” by itself or as part of anothersubstituent, means, unless otherwise stated, a straight or branchedchain hydrocarbon radical, and can include di- and multivalent radicals,having the number of carbon atoms designated (i.e. C₁-C₁₀ or 1- to10-membered means one to ten carbons). If not expressly indicated, thenumber of carbons in an alkyl group may be considered to be C₁-C₁₀, andany of the other ranges and/or specific numbers therein. Examples ofhydrocarbon radicals include, but are not limited to, groups such asmethyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl,sec-butyl, homologs and isomers of, for example, n-pentyl, n-hexyl,n-heptyl, n-octyl, and the like. The term “alkyl,” unless otherwisenoted, is not meant to include derivatives of alkyl such as“heteroalkyl.”

The term “cycloalkyl”, by themselves or in combination with other terms,represent, unless otherwise stated, cyclic versions of “alkyl”. Examplesof cycloalkyl include, but are not limited to, cyclopentyl, cyclohexyl,cycloheptyl, and the like.

The terms “halo” or “halogen” by themselves or as part of anothersubstituent, mean, unless otherwise stated, a fluorine, chlorine,bromine, or iodine atom. Additionally, terms such as “haloalkyl,” aremeant to include monohaloalkyl and polyhaloalkyl. For example, the term“halo(C₁-C₄)alkyl” is mean to include, but not be limited to,trifluoromethyl, 2,2,2-trifluoroethyl, 4-chlorobutyl, 3-bromopropyl, andthe like.

As used herein, the term “substituted” refers to the replacement of ahydrogen atom on a compound with a substituent group. A substituent maybe a non-hydrogen atom or multiple atoms of which at least one is anon-hydrogen atom and one or more may or may not be hydrogen atoms. Forexample, without limitation, substituted compounds may comprise one ormore substituents selected from the group consisting of: R″, OR″,NR″R″′, SR″, halogen, SiR″R″′R″″, OC(O)R″, C(O)R″, CO₂R″, CONR″R″′,NR″′C(O)₂R″, S(O)R″, S(O)₂R″, CN and NO₂. As used herein, each R″, R″′,and R″″ may be selected, independently, from the group consisting of:hydrogen, halogen, oxygen, substituted or unsubstituted heteroalkyl,substituted or unsubstituted aryl, substituted or unsubstituted alkyl,alkoxy or thioalkoxy groups, and arylalkyl groups.

“Moiety” refers to the radical of a molecule that is attached to anothermoiety. In particular, the term “Fluorine moiety” refers to the radicalof a molecule that comprises at least one fluorine radical and/or atom.

Some embodiments of Formula I provide compounds wherein when G¹ isCH(NR¹R²)CF₃, then G³ and G⁴ are independently H or C₁-C₄ alkyl, and G²is H, C₁-C₄ alkyl or cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G² is(CH₂)_(n)CF₂R³, then G¹ and G³ are independently H, C₁-C₄ alkyl, CH₂OHor CH₂NR¹R².

Some embodiments of Formula I provide compounds wherein when G² is H,then G⁴ is H or C₁-C₄ alkyl.

Some embodiments of Formula I provide compounds wherein when G³ is

then G¹ and G⁴ are independently H or C₁-C₄ alkyl.

Some embodiments of Formula I provide compounds wherein when G³ isCH₂CF₃, then G¹ is NR¹R².

Some embodiments of Formula I provide compounds wherein when G¹ isCH₂NR¹R², then G² is (CH₂)_(n)CF₂R³.

Some embodiments of Formula I provide compounds wherein when G¹ isCH(R⁷)CF₂H, then G³ and G⁴ are independently H or C₁-C₄ alkyl, and G² isC₁-C₄ alkyl or cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G¹ isCH(R⁴)CF₃, then G² is C₁-C₄ alkyl or cyclopropyl; provided that when R⁴is H or OH, then G³ is CH₂NR¹R², CH₂-A-OH, CH₂-A-NHR⁹.

Some embodiments of Formula I provide compounds wherein when G¹ isCH(R⁴)CF₃ and R⁴ is H or OH, then G⁴ is halo.

Some embodiments of Formula I provide compounds wherein when G¹ or G³ isCH₂OH, then G² is (CH₂)_(n)CF₂R³.

Some embodiments of Formula I provide compounds wherein when G¹ isNR¹R², then G³ is CH₂CF₃, G⁴ is H or C₁-C₄ alkyl and G² is C₁-C₄ alkylor cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G⁴ isCH(R⁸)CF₃, then G¹ and G³ are independently H or C₁-C₄ alkyl, and G² ishydrogen, C₁-C₄ alkyl or cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G³ isCH₂-A-OH or CH₂-A-NHR, then G⁴ is H or C₁-C₄ alkyl, G² is C₁-C₄ alkyl orcyclopropyl and G¹ is CH(R⁴)CF₃ where R⁴ is H or OH.

Some embodiments of Formula I provide compounds wherein when G³ isCH₂NR¹R², and G² is C₁-C₄ alkyl or cyclpropyl, then G⁴ is H or C₁-C₄alkyl, and G¹ is CH(R⁴)CF₃ where R⁴ is H or OH.

Some embodiments of Formula I provide compounds wherein when G¹ isCH(R⁴)CF₃ and R⁴ is H or OH, then either G³ is CH₂NR¹R² or G⁴ is halo.

Some embodiments of Formula I provide compounds wherein when G³ isCH(R⁶)CF₃, then G¹ is CH₂NR¹R² or NR¹R².

Some embodiments of Formula I provide compounds having a structure ofFormula II

wherein

G¹ is H, C₁-C₄ alkyl, —CH₂OH, or —CH₂NR¹R²;

G³ is H, C₁-C₄ alkyl, —CH₂OH, or —CH₂NR¹R²;

G⁴ is H, C₁-C₄ alkyl, or halo;

R¹ and R² are either (a) two independent groups or (b) together form asingle ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from thegroup consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, andpropargyl;

R¹ and R², when together form a single ring group including the N towhich they are bonded, are selected from the group consisting of:piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, andpiperidinyl;

n is 1, 2 or 3; and

R³ is H, or F.

Some embodiments of Formula II provide compounds wherein n is 1.

Some embodiments of Formula II provide compounds wherein G⁴ is H.

Some embodiments of Formula II provide compounds wherein R³ is H.

Some embodiments of Formula II provide compounds wherein R³ is F.

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl,and G¹ is H. This compound may be termed5-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, andG¹ is methyl. This compound may be termed3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, andG¹ is ethyl. This compound may be termed2-ethyl-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, andG¹ is H. This compound may be termed3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, andG¹ is CH₂OH. This compound may be termed3-hydroxy-2-(hydroxymethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl,and G¹ is CH₂NR¹R² wherein R¹ is methyl and R² is methyl. This compoundmay be termed2-[(dimethylamino)methyl]-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, andG¹ is CH₂NR¹R² wherein R¹ is methyl and R² is methyl. This compound maybe termed2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl,and G¹ is CH₂OH. This compound may be termed3-hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl,and G¹ is CH₂NR¹R² wherein NR¹R² is piperdinyl. This compound may betermed3-hydroxy-6-methyl-2-(piperidin-1-ylmethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is H, R³ is H, G² is difluoroethyl, and G¹is methyl. This compound may be termed1-(2,2-difluoroethyl)-3-hydroxy-2-methylpyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is methyl, R³ is H, G² is difluoroethyl,and G¹ is H. This compound may termed1-(2,2-difluoroethyl)-5-hydroxy-2-methylpyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is acompound in which G⁴ is H; G³ is methyl, R³ is H, G² is difluoroethyl,and G¹ is CH₂NR¹R², R¹ is methyl and R² is methyl. This compound maytermed1-(2,2-difluoroethyl)-2-[(dimethylamino)methyl]-3-hydroxy-6-methylpyridin-4(1H)-one,

Some embodiments of Formula I provide compounds having a structure ofFormula III

wherein

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, C₁-C₄ alkyl, CH₂-A-OH, CH₂-A-NHR⁹, or CH₂NR¹R²;

G⁴ is H, C₁-C₄ alkyl, or halo;

R⁴ is selected from the group consisting of: H, OH, NR¹R², imidazole,1,2,4-triazole, piperazine, N—C₁-C₄ alkylpiperazine, N-benzylpiperazine,N-phenylpiperazine, 2-pyridylpiperazine, and -A-NH—R¹⁰; and when R⁴ isNR¹R², imidazole, 1,2,4-triazole, piperazine, N—C₁-C₄ alkylpiperazine,N-benzylpiperazine, N-phenylpiperazine, 2-pyridylpiperazine, or-A-NH—R¹⁰, a point of attachment of R⁴ to the —CH moiety of G¹ is anN-atom of R⁴;

R¹ and R² are either (a) two independent groups or (b) together form asingle ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from thegroup consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, andpropargyl;

R¹ and R², when together form a single ring group including the N towhich they are bonded, are selected from the group consisting of:piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, andpiperidinyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and

R⁹ and R¹⁰ are independently H, or C₁-C₄ alkyl.

Compounds of Formula III include compounds of Formula I wherein G¹ isCH(R⁴)CF₃. Compounds Formula III may be further subdivided into threemain subcategories, formula IIIA, formula IIIB and formula IIIC.

Compounds of formula IIIA are compounds of Formula III wherein G² isC₁-C₄ alkyl, or cyclopropyl; G³ is H, or C₁-C₄ alkyl; and R⁴ is selectedfrom the group consisting of: NR¹R², imidazole, 1,2,4-triazole,piperazine, N—C₁-C₄ alkylpiperazine, N-benzylpiperazine,N-phenylpiperazine, 2-pyridylpiperazine and -A-NH—R¹⁰.

Some embodiments of formula IIIA are compounds wherein G² is methyl.

Some embodiments of formula IIIA are compounds wherein G³ is H and G⁴ isH.

Some embodiments of formula IIIA are compounds wherein R⁴ is NR¹R².

An example of a particular illustrative embodiment of Formula IIIA is acompound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is A-NHR¹⁰, A isD-alanyl and R¹⁰ is methyl. This compound may be termedN-methyl-N²-[2,2,2-trifluoro-1-(3-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)ethyl]-D-alaninamideand has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is acompound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R¹ ismethyl, and R² is methyl. This compound may be termed2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is acompound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R¹ ismethyl, and R² is propargyl. This compound may be termed3-hydroxy-1-methyl-2-{2,2,2-trifluoro-1-[methyl(prop-2-yn-1-yl)amino]ethyl}pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is acompound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R¹ is H,R² is cyclopropyl. This compound may be termed2-[1-(cyclopropylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is acompound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R¹ is H,R² is allyl. This compound may be termed3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(prop-2-en-1-ylamino)ethyl]pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is acompound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², NR¹R² ispiperidinyl. This compound may be termed3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is acompound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², NR¹R² isN-methylpiperazinyl. This compound may be termed3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridin-4(1H)-oneand has the following structure:

Compounds of formula IIIB are compounds of Formula III wherein G³ isCH₂-A-OH, CH₂-A-NHR⁹, or CH₂NR¹R²; G⁴ is H, or C₁-C₄ alkyl; and R⁴ is H,or OH.

Some embodiments of formula IIIB are compounds wherein G² is methyl.

Some embodiments of formula IIIB are compounds wherein G⁴ is H.

An example of a particular illustrative embodiment of Formula IIIB is acompound in which G⁴ is H; G³ is CH₂NR¹R², R¹ is methyl, R² is methyl,G² is methyl, and R⁴ is H. This compound may be termed6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIB is acompound in which G⁴ is H; G³ is CH₂NR¹R², R¹ is methyl, R² is methyl,G² is methyl, and R⁴ is OH. This compound may be termed6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIB is acompound in which G⁴ is H; G³ is CH₂-A-OH, A is L-alanyl, G² is methyland R⁴ is OH. This compound may be termedN-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-L-alanineand has the following structure:

An example of a particular illustrative embodiment of Formula IIIB is acompound in which G⁴ is H; G³ is CH₂-A-NHR⁹, A is L-alanyl, R⁹ ismethyl, G² is methyl and R⁴ is OH. This compound may be termedN²-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-N-methyl-L-alaninamideand has the following structure:

Compounds of formula IIIC are compounds of Formula III wherein G³ is Hor C₁-C₄ alkyl; and G⁴ is halo.

Some embodiments of formula IIIC are compounds wherein G² is methyl.

Some embodiments of formula IIIC are compounds wherein G⁴ is chloro.

An example of a particular illustrative embodiment of Formula IIIC is acompound in which G⁴ is chloro, G³ is methyl, G² is methyl, and R⁴ isOH. This compound may be termed3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is acompound in which G⁴ is chloro, G³ is methyl, G² is methyl, and R⁴ is H.This compound may be termed3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is acompound in which G⁴ is chloro, G³ is methyl, G² is methyl, R⁴ is NR¹R²,R¹ is methyl and R² is methyl. This compound may be termed3-chloro-6-[1-(dimethylamino)-2,2,2-trifluoroethyl]-5-hydroxy-1,2-dimethylpyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is acompound in which G⁴ is chloro, G³ is H, G² is methyl, R⁴ is NR¹R², R¹is methyl and R² is methyl. This compound may be termed5-chloro-2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is acompound in which G⁴ is chloro, G³ is H, G² is methyl, R⁴ is NR¹R², andNR¹R² is piperidinyl. This compound may be termed5-chloro-3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is acompound in which G⁴ is chloro, G³ is H, G² is methyl, R⁴ is H. Thiscompound may be termed5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-oneand has the following structure:

Some embodiments of Formula I provide compounds having a structure ofFormula IV

wherein

G¹ is H, or C₁-C₄ alkyl;

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, or C₁-C₄ alkyl;

R⁸ is selected from the group consisting of: NR¹R², imidazole,1,2,4-triazole, piperazine, N—C₁-C₄ alkylpiperazine, N-benzylpiperazine,N-phenylpiperazine, 2-pyridylpiperazine, and -A-NH—R¹⁰; a point ofattachment of R⁸ to the —CH moiety of G¹ is an N-atom of R⁸;

R¹ and R² are either (a) two independent groups or (b) together form asingle ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from thegroup consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, andpropargyl;

R¹ and R², when together form a single ring group including the N towhich they are bonded, are selected from the group consisting of:piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, andpiperidinyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and

R¹⁰ is H, or C₁-C₄ alkyl.

Some embodiments of Formula IV are compounds wherein G³ is H.

Some embodiments of Formula IV are compounds wherein G¹ is methyl.

An example of a particular illustrative embodiment of Formula IV is acompound in which G³ is H; G¹ is methyl, G² is H, R⁸ is A-NHR¹⁰, A isL-alanyl, and R¹⁰ is methyl. This compound may be termedN-methyl-N²-[2,2,2-trifluoro-1-(5-hydroxy-6-methyl-4-oxo-1,4-dihydropyridin-3-yl)ethyl]-L-alaninamideand has the following structure:

An example of a particular illustrative embodiment of Formula IV is acompound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; R¹is methyl, and R² is methyl. This compound may be termed5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IV is acompound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; R¹is H, and R² is methyl. This compound may be termed3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(methylamino)ethyl]pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IV is acompound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²;NR¹R² is piperidinyl. This compound may be termed3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IV is acompound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²;NR¹R² is imidazolyl. This compound may be termed3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(1H-imidazol-1-yl)ethyl]pyridin-4(1H)-oneand has the following structure:

An example of a particular illustrative embodiment of Formula IV is acompound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; andNR¹R² is N-methylpiperazinyl. This compound may be termed3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridin-4(1H)-onehydrochloride and has the following structure:

Some embodiments of Formula I provide compounds having a structure ofFormula V

wherein

G¹ is CH₂NR¹R², or NR¹R²;

G² is C₁-C₄ alkyl, or cyclopropyl;

G⁴ is H, or C₁-C₄ alkyl;

R⁶ is H, or OH; and

R¹ and R² are either (a) two independent groups or (b) together form asingle ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from thegroup consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, andpropargyl;

R¹ and R², when together form a single ring group including the N towhich they are bonded, are selected from the group consisting of:piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, andpiperidinyl.

Some embodiments of Formula V are compounds wherein G⁴ is H.

Some embodiments of Formula V are compounds wherein G² is methyl.

An example of a particular illustrative embodiment of Formula V is acompound in which G⁴ is H; R⁶ is H, G² is methyl, G¹ is NR¹R², R¹ ismethyl and R² is methyl. This compound may be termed2-(dimethylamino-3-hydroxy-1-methyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

An example of a particular illustrative embodiment of Formula V is acompound in which G⁴ is H; R⁶ is OH, G² is methyl, G¹ is CH₂NR¹R², R¹ ismethyl and R² is methyl, R¹ is methyl and R² is methyl. This compoundmay be termed2-[(dimethylamino)methyl]-3-hydroxy-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one

Some embodiments of Formula I provide compounds having a structure ofFormula VI:

wherein

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, or C₁-C₄ alkyl;

G⁴ is H, or C₁-C₄ alkyl;

R⁷ is selected from the group consisting of: H, OH, NR¹R², imidazolyl,1,2,4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl,N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl, and—CH₂-A-NH—R¹⁰; and when R⁷ is NR¹R², imidazolyl, 1,2,4-triazolyl,piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl,N-phenylpiperazinyl, 2-pyridylpiperazinyl or —CH₂-A-NH—R¹⁰, a point ofattachment of R⁷ to the —CH moiety of G¹ is an N-atom of R⁷;

R¹ and R² are either (a) two independent groups or (b) together form asingle ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from thegroup consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, andpropargyl;

R¹ and R², when together form a single ring group including the N towhich they are bonded, are selected from the group consisting of:piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, andpiperidinyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and

R¹⁰ is H, C₁-C₄ alkyl.

An example of a particular illustrative embodiment of Formula VI is acompound in which G³ is H, G⁴ is H, G² is methyl, G¹ is CH(R⁷)CF₂H, andR⁷ is hydroxy. This compound may be termed2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one andhas the following structure:

Another example of a particular illustrative embodiment of Formula VI isa compound in which G³ is H, G⁴ is H, G² is methyl, G¹ is CH(R⁷)CF₂H,and R⁷ is H. This compound may be termed2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has thefollowing structure:

Some embodiments of Formula I provide compounds having a structure ofFormula VII:

wherein

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, or C₁-C₄ alkyl; and

G⁴ is H, or C₁-C₄ alkyl.

Particular illustrative embodiments of Formula VII include compounds inwhich G² is methyl, G³ is H, G⁴ is H, R⁵ is methyl, and R⁶ is H or OH.An example of a particular illustrative embodiment of Formula VII is acompound in which G² is methyl, G³ is H, G⁴ is H, R⁵ is methyl, and R⁶is OH. This compound may be termed3-hydroxy-1-methyl-2-(1,1,1-trifluoro-2-hydroxypropan-2-yl)pyridin-4(1H)-oneand has the following structure:

In some embodiments, compounds of the present invention comprise a3-hydroxypyridin-4-one moiety having a halo group, attached to the C5position of the ring (G⁴ is halo), and a trifluoroethyl moiety, at theG¹ or G² or G³ position. In some of these embodiments, the halo group isa chloro group.

The following Schemes 1-9 depict examples of methods that can be usedfor the preparation of compounds of the Formulas I, II, III, IV, V, VI,and VII. All of the starting materials are prepared by proceduresdescribed in these schemes, by procedures well known to one of ordinaryskill in organic chemistry or can be obtained commercially. All of thefinal compounds of the present invention may be prepared by proceduresdescribed in these schemes or by procedures analogous thereto.

The compounds of Formula I wherein G²=—(CH₂)_(n)CF₂R³ can be prepared bythe method as shown in Scheme 1, or by the methods given in the examplesor by analogous methods. As shown in Scheme 1, compound (1a) wherein G¹is H or C₁-C₄ alkyl, G³ is H or C₁-C₄ alkyl, G⁴ is H or C₁-C₄ alkyl, maybe treated with sodium hydroxide and benzyl bromide or benzyl chlorideto give the compound (1b). The amine insertion with compound (1b) may beconducted with trifluoroethylamine hydrochloride and an organic basesuch as pyridine in an inert solvent to give compound (1c) wherein n is1 and R³ is F, which may be deprotected either by hydrolysis withhydrochloric acid solution or by catalytic hydrogenation over 10% Pd/Cto give a compound of formula II. Compound of formula II is a compoundof Formula I wherein R³ is F, and n is 1.

As an illustrative example, the compounds of Formula I wherein G¹ is H,G³ is H, G⁴ is H, n is 1, R³ is F can be prepared by the method shown inScheme 2.

Compound (2a) may be reacted with CF₂R³CH₂NH₂ in water to give acompound (2b), which upon heating in inert organic solvent such asdimethylformamide, affords the compound (2c), which may be deprotectedwith catalytic hydrogenation using hydrogen, catalytic palladium oncharcoal to give a compound (2d), which is compound of Formula IIwherein n is 1, G¹ is H, G³ is H, G⁴ is H. Compound (2d) is also acompound of formula I wherein G¹ is H, G³ is H, G⁴ is H, n is 1, G² is—CH₂CF₂R³.

The compounds of Formula I wherein n is 1, G² is CH₂CF₂R³, G¹ isCH₂NR¹R², CH₂OH, or a compound of formula II wherein G¹ is CH₂OH orCH₂NR¹R² are prepared by the method as shown in Scheme 3.

Compound (3a) may be reacted with formaldehyde and sodium hydroxide togive compound (3b). Reaction of compound (3b) with thionyl chloride inan inert solvent such as acetonitrile affords the chloro compound (3c),which may be quenched with an amine R¹R²NH to give the compound ofFormula (3d), which is a compound of Formula I when G¹ is CH₂NR¹R². Thecompound may be isolated by conventional means. Alternatively, when n=1,compound (3a) may be reacted directly with bis-(dimethylamino)methane togive the compound (3d), which is a compound of Formula I wherein G¹ isCH₂N(CH₃)₂.

The compounds of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ is NR¹R², OH, Hor the compounds of Formula III wherein R⁴ is NR¹R², OH, H; G² is H,C₁-C₄ alkyl; G³ is H, C₁-C₄ alkyl; G⁴ is H, C₁-C₄ alkyl, halo; may beprepared by the method as shown in Scheme 4. For illustration purposes,the scheme shows the synthesis of a compound of Formula I or IIIA orIIIC wherein G³ is H.

Compound (4a) may be reacted with sodium hypochlorite in 2N NaOH to givethe chloro derivative (4b), which may then be reacted with potassiumcarbonate and methyl iodide in dimethylformamide to give the N-methylcompound (4c). TEMPO oxidation in an inert solvent such as acetoneaffords the carboxylic acid (4d). Acid deprotection and decarboxylationwith 6N hydrochloric acid affords the starting material (4e). Compound(4e) may be reacted with CF₃CH(OCH₃)OH to give the diol (4f). Treatmentof thionyl chloride and pyridine yields the chloride (4g). Upon reactingcompound (4g) with sodium borohydride, compound (4h) may be formed.Compound (4i) is obtained from the quenching of the chloride (4g) withR¹R²NH.

Compound (4i) is a compound of Formula I wherein G¹ is CH(R⁴)CF³, R⁴ isNR¹R² wherein R¹, R² are methyl, G² is methyl, G³ is H, and G⁴ ischloro. It is also a compound of formula III wherein R⁴ is NR¹R² whereinR¹, R² are methyl, G² is methyl, G³ is H, and G⁴ is chloro.

Compound (4h) is a compound of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ isH, G² is methyl, G³ is H, G⁴ is chloro. It is also a compound of formulaIII wherein R⁴ is H, G² is methyl, G³ is H, G⁴ is chloro.

Compound (4f) is a compound of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ isOH, G² is methyl, G³ is H, G⁴ is chloro. It is also a compound offormula III wherein R⁴ is OH, G² is methyl, G³ is H, G⁴ is chloro.

The compound of Formula I wherein G⁴ is CH(R⁸)CF₃, R⁸ is NR¹R², G³ is H,G¹ is C₁-C₄ alkyl, G² is C₁-C₄ alkyl or the compound of formula IVwherein R⁸ is NR¹R², G³ is H, G¹ is methyl, G² is methyl may be preparedaccording to the representative procedures as outline in Scheme 5 below:

Compound (5c) may be prepared according to the procedure outlined inWO20080242706. Reaction of compound (5c) with thionyl chloride gives(5d) which may be quenched with an amine R¹R²NH to give compound (5e).Compound (5e) is a compound of Formula I wherein G⁴=CH(R⁸)CF₃, R⁸ isNR¹R², G³ is H, G¹ is methyl, G² is methyl. It is also a compoundformula IV wherein R⁸ is NR¹R², G³ is H, G¹ is methyl, G²=methyl. WhenR¹ is methyl, R² is methyl, compound (5e) has the chemical name5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one.

A compound of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ is H or OH, G² isC₁-C₄ alkyl, G³ is CH₂NR¹R², G⁴ is H or a compound of formula IIIBwherein R⁴ is H or OH, G² is methyl, G³ is CH₂NMe₂, G⁴ is H may beprepared according to the representative procedures as outline in Scheme6 below:

Alcohol (6a) may be converted to the chloro compound (6b) with thionylchloride. Upon quenching with dimethylamine, compound (6c) is formed,which may be deprotected by catalytic hydrogenation with palladium oncharcoal to give compound (6d). Reaction of compound (6d) withCF₃CH(OH)OCH₃ and potassium carbonate affords the diol (6e), whichreacts with thionyl chloride to give the compound (6f). Reduction of thechloro compound with catalytic hydrogenation yields the compound (6g).Compound (6e) is a compound of Formula I wherein G⁴ is H, G³ isCH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, G¹ is CH(R⁴)CF₃, R⁴is OH. It is also a compound of formula IIIB wherein G⁴ is H, G³ isCH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, R⁴ is OH. Compound(6e) has the chemical name6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one.

Compound (6g) is a compound of Formula I wherein G⁴ is H, G³ isCH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, G¹ is CH(R⁴)CF₃, R⁴is H. It is also a compound of formula IIIB wherein G⁴=H, G³=CH₂NR¹R²,R¹ is methyl, R² is methyl, G² is methyl, G¹R⁴ is H. Compound (6e) hasthe chemical name6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one.

A compound of Formula I wherein G³ is H or C₁-C₄ alkyl; G⁴ is H, orC₁-C₄ alkyl; G¹ is CH(R⁷)CF₂H, or a compound of formula VI wherein G³ isH or C₁-C₄ alkyl; G⁴ is H, or C₁-C₄ alkyl; R⁷ is H, OH, NR¹R² may beprepared according to the representative procedures as outline in Scheme7 below:

Compound (7a) may be reacted with difluoroacetaldehyde ethyl hemiacetaland potassium carbonate to give the compound of Formula (7b). Thisintermediate may be converted to compounds (7e) and (7d) in a similarmanner as described for the conversion of compound (4f) to (4h) and (4i)(Scheme 4). (7b) is a compound of Formula I wherein G¹ is CH(R⁷)CF₂H, R⁷is OH or a compound of formula VI wherein R⁷ is OH. (7e) is a compoundof Formula I wherein R⁷ is H, or a compound of formula VI wherein R⁷ isH and (7d) is a compound of Formula I wherein G¹ is CH(R⁷)CF₂H, R⁷ isNR¹R² or a compound of formula VI wherein R⁷ is NR¹R².For example, whenG² is methyl, G³ is H, G⁴ is H in scheme 1, the compound (7e) is2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and thecompound (7b) is2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one.

The compound of Formula I wherein G³ is CH(R⁶)CF₃, R⁶ is H, G¹ is NR¹R²or a compound of formula V wherein R⁶ is H, G³ is CH₂CF₃, G¹ is NR¹R²may be prepared according to the representative procedures as outline inScheme 8 below:

Compound (8a) wherein G² is C₁-C₄ alkyl, G⁴ is H may be first reactedwith thionyl chloride in an inert solvent. Quenching the reaction withan amine R¹R²NH affords the compound (8b). The structure of (8b) may beconfirmed by NMR and MS spectroscopy. The compound of Formula (8b) is acompound of Formula I wherein G² is C₁-C₄ alkyl, G⁴ is H, or C₁-C₄alkyl, R⁶ is H; or a compound of formula V wherein R⁶ is H, G² is C₁-C₄alkyl, G¹ is NR¹R², G⁴ is H. For example, the compound5-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-oneis a compound (8a) wherein G⁴ is H, G² is methyl. Compound (8a) can beconverted to2-(dimethylamino)-3-hydroxy-1-methyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,a compound of (8b) wherein R¹ is methyl, R² is methyl, G² is methyl, G⁴is hydrogen with dimethylamine according to the method described inScheme 8.

Compound of Formula I wherein G¹ is C(R⁵)(R⁶)CF₃, R⁵ is C₁-C₄ alkyl, R⁶is OH or a compound of formula VII wherein R⁵ is C₁-C₄ alkyl, R⁶ is OHmay be prepared according to the representative procedures as shown inScheme 9 below:

Compound (9a) may be first reacted with Dess-Martin oxidation reagent togive compound 9b, which may be reacted with the Grignard reagent R⁵—MgClor R⁵—MgBr to give compound 9c. Catalytic hydrogenation of I3 withpalladium on charcoal affords compound 9d, which is a compound ofFormula I when R⁵ is C₁-C₄ alkyl, R⁶ is OH. For example, in when G² ismethyl, G³ is H, G⁴ is H, R⁵ is methyl in Scheme 9, the product (9d) isthe compound3-hydroxy-1-methyl-2-(1,1,1-trifluoro-2-hydroxypropan-2-yl)pyridin-4(1H)-one.

Many compounds of this invention or for use in this invention may beformed as salts. In such cases, pharmaceutical compositions inaccordance with this invention may comprise a salt of such a compound,preferably a physiologically acceptable salt, which are known in theart. Pharmaceutical preparations will typically comprise one or morecarriers acceptable for the mode of administration of the preparation,be it by injection, inhalation, topical administration, lavage, or othermodes suitable for the selected treatment. Suitable carriers are thoseknown in the art for use in such modes of administration.

Suitable pharmaceutical compositions may be formulated by means known inthe art and their mode of administration and dose determined by theskilled practitioner. For parenteral administration, a compound may bedissolved in sterile water or saline or a pharmaceutically acceptablevehicle used for administration of non-water soluble compounds such asthose used for vitamin K. For enteral administration, the compound maybe administered in a tablet, capsule or dissolved in liquid form. Thetablet or capsule may be enteric coated, or in a formulation forsustained release. Many suitable formulations are known, including,polymeric or protein microparticles encapsulating a compound to bereleased, ointments, pastes, gels, hydrogels, or solutions which can beused topically or locally to administer a compound. A sustained releasepatch or implant may be employed to provide release over a prolongedperiod of time. Many techniques known to one of skill in the art aredescribed in Remington: the Science & Practice of Pharmacy by AlfonsoGennaro, 20^(th) ed., Lippencott Williams & Wilkins, (2000).Formulations for parenteral administration may, for example, containexcipients, polyalkylene glycols such as polyethylene glycol, oils ofvegetable origin, or hydrogenated naphthalenes. Biocompatible,biodegradable lactide polymer, lactide/glycolide copolymer, orpolyoxyethylene-polyoxypropylene copolymers may be used to control therelease of the compounds. Other potentially useful parenteral deliverysystems for modulatory compounds include ethylene-vinyl acetatecopolymer particles, osmotic pumps, implantable infusion systems, andliposomes. Formulations for inhalation may contain excipients, forexample, lactose, or may be aqueous solutions containing, for example,polyoxyethylene-9-lauryl ether, glycocholate and deoxycholate, or may beoily solutions for administration in the form of nasal drops, or as agel.

Compounds or pharmaceutical compositions in accordance with thisinvention or for use in this invention may be administered by means of amedical device or appliance such as an implant, graft, prosthesis,stent, etc. Also, implants may be devised which are intended to containand release such compounds or compositions. An example would be animplant made of a polymeric material adapted to release the compoundover a period of time.

An “effective amount” of a pharmaceutical composition according to theinvention includes a therapeutically effective amount or aprophylactically effective amount. A “therapeutically effective amount”refers to an amount effective, at dosages and for periods of timenecessary, to achieve the desired therapeutic result, such as improvediron distribution or reduced levels of toxic iron. A therapeuticallyeffective amount of a compound may vary according to factors such as thedisease state, age, sex, and weight of the subject, and the ability ofthe compound to elicit a desired response in the subject. Dosageregimens may be adjusted to provide the optimum therapeutic response. Atherapeutically effective amount is also one in which any toxic ordetrimental effects of the compound are outweighed by thetherapeutically beneficial effects. A “prophylactically effectiveamount” refers to an amount effective, at dosages and for periods oftime necessary, to achieve the desired prophylactic result, such as suchas improved iron distribution or reduced levels of toxic iron.Typically, a prophylactic dose is used in subjects prior to or at anearlier stage of disease, so that a prophylactically effective amountmay be less than a therapeutically effective amount.

It is to be noted that dosage values may vary with the severity of thecondition to be alleviated. For any particular subject, specific dosageregimens may be adjusted over time according to the individual need andthe professional judgement of the person administering or supervisingthe administration of the compositions. Dosage ranges set forth hereinare exemplary only and do not limit the dosage ranges that may beselected by medical practitioners. The amount of active compound(s) inthe composition may vary according to factors such as the disease state,age, sex, and weight of the subject. Dosage regimens may be adjusted toprovide the optimum therapeutic response. For example, a single bolusmay be administered, several divided doses may be administered over timeor the dose may be proportionally reduced or increased as indicated bythe exigencies of the therapeutic situation. It may be advantageous toformulate parenteral compositions in dosage unit form for ease ofadministration and uniformity of dosage.

In general, compounds of the invention should be used without causingsubstantial toxicity. Toxicity of the compounds of the invention can bedetermined using standard techniques, for example, by testing in cellcultures or experimental animals and determining the therapeutic index,i.e., the ratio between the LD₅₀ (the dose lethal to 50% of thepopulation) and the LD₁₀₀ (the dose lethal to 100% of the population).In some circumstances however, such as in severe disease conditions, itmay be necessary to administer substantial excesses of the compositions.

As used herein, a “subject” may be a human, non-human primate, rat,mouse, cow, horse, pig, sheep, goat, dog, cat, etc. The subject may besuspected of having or at risk for having a medical condition related toa toxic concentration of iron. The medical condition related to a toxicconcentration of iron may be selected from the group consisting of:cancer, pulmonary disease, progressive kidney disease and Friedreich'sataxia. Diagnostic methods for various medical conditions related to atoxic concentration of iron and the clinical delineation of variousmedical conditions related to a toxic concentration of iron and theirdiagnoses are known to those of ordinary skill in the art.

An important property of iron is its ability to donate and accept anelectron readily between the ferrous (Fe²⁺) and ferric (Fe³⁺) species.This can be a liability as iron can play a critical role in both theFenton and the Haber-Weiss reactions in catalyzing the production ofhydroxyl radicals. Thus, in conditions wherein the reduction of Fe(III)to Fe(II) is facilitated, the generation of these active oxygen species(hydroxyl radical) can cause considerable damage to biomolecules in theliving system that include cellular membranes, proteins and DNA.

Fe³⁺+O₂ ⁻→Fe²⁺+O₂  (reduction of metal)

Fe²⁺+H₂O₂→Fe³⁺+OH⁻+OH.  (Fenton reaction)

H₂O₂+O₂ ⁻→O₂+OH⁻+OH.  (Haber-Weiss cycle)

Iron chelators can either inhibit or facilitate the participation ofiron in the Fenton and Haber-Weiss reactions that produce toxic oxygenradicals. Since certain iron chelators can potentially promote Fe³⁺reduction, early evaluations on whether the chelator can promote,prevent, or has no effect on Fe³⁺ reduction are essential.

There are several quintessential methods and chemical models that havebeen used to study the capacity of the chelators to restrict theparticipation of iron in radical generating reactions via the indirectobservation of radical formation (Dean R T and Nicholson P (1994) FreeRadical Res 20:83-101 and Gutteridge J M (1990) Free Radical Res Commun9:119-125). The use of cyclic voltammetry, and benzoic acidhydroxylation assay in screening the compounds of formula I areillustrated in the examples 30 and 31, respectively.

The neuroprotective effect of compounds of formula I is demonstrated inthe hydrogen peroxide induced apoptosis in SH-SY5Y neuroblastoma cellsassay in example 32A. The protective effective of compounds of formula Iagainst endogenously produced Aβ toxicity is shown in example 32B.Cytotoxicity was also induced by the dopaminergic neurotoxin MPP⁺ onSV-NRA cells. The neuroprotective action of selected compounds offormula I is further demonstrated in MPP⁺ treated SV-NRA cells inExample 33 below.

In-vivo pharmacokinetic (PK) and blood brain barrier (BBB) studies wereconducted in male Sprague-Dawley rats using cassette dosing via oraladministration. The topic of cassette dosing has been reviewed byManitpisitkul, P. and White, R. E. (August 2004), Drug Discovery, Vol 9.No. 15, pp. 652-658. The results are summarized in the Table below:

Oral Cassette Dosing Studies of a compound of formula I in maleSprague-Dawley rats, AUCs is normalized to 1 mg/kg dose AUC AUC AUCbrain* plasma* brain/AUC CL Cpd (ug-h/mL) (ug-h/mL) plasma (L/h-kg)Apo6995 0.30 0.26 1.2 3.89 Apo7030 0.59 (cal.) 0.59 1.00 1.68 Apo70410.45 0.60 0.75 1.67 Apo7080 0.7 0.92 0.76 1.09 Apo7067 0.74 0.5 1.502.00 Apo7056 0.77 1.38 0.56 0.72 Clioquinol 0.042 0.028 1.5 3.52

List of Compounds of Formula I Tested in Cassette Dosing BBB Studies

Cpd G⁴ G³ G² G¹ Apo6995 H H CF₃CH₂ CH₃ Apo7030 H H CF₃CH₂ CH₃CH₂ Apo7041H H CH₃ CF₃CH(NMe₂)— Apo7080 H H CH₃ CF₂HCH₂— Apo7067 H H CF₃CH₂Me₂NCH₂— Apo7056 CF₃CH(NHMe)— H CH₃ CH₃

It is generally accepted that 1,2-dimethyl-3-hydroxypyrid-4-one and itsalkyl derivatives are bidentate ligands (Ls) and react with Fe(III) toform neutral 1:3 chelates. In the speciation plot as shown in FIG. 4,the percentage of FeL₃ species is close to 100 at pH 7.4 whendeferiprone is used as ligand. The resulting Fe chelate (FeL₃) is notredox active, as evidenced by cyclic voltammetry analysis. However, ifthe pH is lowered to 6.0, a mixture of FeL₂ ⁺ and FeL₃ species are nowpresent in solution. Deferiprone (1,2-dimethyl-3-hydroxypyrid-4-one) iseffective on the removal of Fe(III) at pH>7.2 at physiologicalconditions, but at a lower pH, deferiprone and its alkyl derivatives aresignificantly less effective.

Hider et al. (J. Pharm. Pharmacol. 2000, 52, 263-273; European Journalof Medicinal Chemistry 2008, 42, 1035-1047) reported the use ofalkylamino derivatives of 3-hydroxypyridin-4-ones. Two speciation plotsare illustrated with two different concentration of2-ethyl-3-hydroxy-1-[2-(piperidin-1-yl)ethyl]pyridin-4(1H)-one [L] at1×10⁻⁵ M and 7×10⁻⁴ M, respectively, while maintaining the concentrationof [Fe] fixed at 1×10⁻⁶M. The FeL₃ chelate has a broader stabilityprofile only at pH>5 and above, and when [L] is 7×10⁻⁴ M (FIG. 9 of J.Pharm. Pharmacol. 2000, 52, 271). However, at a concentration of [L] at1×10⁻⁵ M, the FeL₃ stability profile is very similar to that ofFe-deferiprone complex.

Selected amino compounds of this invention such as Apo7041 have FeL₃chelate stability that extends from pH 5 and above. Analysis ofphotospectroscopic data of the Fe chelate shows that the fluorinated3-hydroxypyridin-4-one with weak base amino group is a stronger protonacceptor than the oxygen atom in the Fe—O bond of the chelate. BetweenpH 5 to 7.2, the Fe(III) is trapped as a ferric chelate in the form ofFeL₃ and FeL₃H. The Apo7041 speciation plot in FIG. 5 showed that noFeL₂ is present at above pH 5.0. In addition, the ligand concentration[L] does not affect the outcome of speciation plot in this chemicalstudy.

The number of weak basic amines available as proton acceptor is three inthe ferric chelate. Before the scission of the Fe—O bond of the 1:3chelate, all three amino groups have to be protonated. Thecharacteristic of this compound behaving as an internal proton sinkresults in an improvement in the chelate stability at low pH, whichoffers clear advantage over the neutral 3-hydroxypyridin-4-ones such asdeferiprone. FIG. 6 and FIG. 7 outline the comparison of the neutral andbasic amine chelates. Upon dropping the pH to around 5.0, a significantamount of FeL₃ decomposed to give FeL₂ via the cleavage of the Fe—O bondwhen L is a neutral ligand. However, the chelates from the basic aminesderivatives of formula I in this invention are stable at lower pHs.

Deferiprone undergoes Phase II metabolism resulting in extensiveglucuronidation at the C3 oxygen of the 3-hydroxypyridin-4-one skeleton.Therefore, a high oral dose of deferiprone is required to achievetherapeutic effect. Selected compounds of this invention are designedspecifically to block the C3 oxygen from glucuronidation by theintroduction of a bulky C3 or C5 trifluroroethyl moiety substituted withan amine derivative. In modeling studies, a simple trifluoroethyl grouphas the same steric bulk as an isopropyl group. For example, the stericbulk of a 1-dimethylamino-2-trifluoroethyl substituent may prevent theC3 O-glucuronidation without affecting the formation of the ferricchelate FeL₃. The 3D modeling of the compound Fe(Apo7041)₃ is shown inFIG. 8.

Cyclic voltammetry experiments show that a stable Fe(Apo7041)₃ is formedwith E_(1/2)=−731 mV (FIG. 2). The data showed that the Fe(Apo7041)₃ isnon redox active and is a stable chemical entity. The cumulative logβ₁₃₀ value of Apo7041 for Fe(III) is 38.8 (Table 29B in example 29B),which is relatively higher than that of deferiprone with a value of37.24 (Table 1). Unlike other amine derivatives of 3-hydroxypyridin-4-onreported by Hider et al., the pKa of the C2-amino moiety of Apo7041 is3.5 in 0.1 M aqueous NaCl. Thus, at pH 3.5, the protonated form and thenon-protonated form of the amine exist in a 1:1 ratio. With anincremental unit increase in pH, there will be significantly more freebase present in the media.

Selected amino derivatives of this invention have better metalselectivity when compared to deferiprone. The metal binding propertiesof Apo7041 are compared to those of deferiprone in Table 1. For example,the cumulative log β₁₂₀ for Zn(II) and Cu(II) are 13.2 and 17.3,respectively, for Apo7041, which are 2 to 3 orders of magnitude lower ascompared to those for deferiprone at 15.0 and 20.5, respectively, in0.1M aqueous NaCl/MeOH, 1/1, v/v. Thus, the amine derivatives of thisinvention are selective for Fe(III). The ranking according to bindingaffinities are Fe(III)>>Cu(II)>>Zn(II).

TABLE 1 Comparison of the metal binding properties of the amino compoundApo7041 and deferiprone.^(a,b)                     PropertiesDeferiprone        

Apo7041  

pKa^(a) pKa₁ = 10.6 pKa₁ = 10.1 pKa₂ = 4.0 pKa₂ = 3.2 pKa₃ = 2.0 Cu²⁺chelation^(a) Logβ₁ = 10.8 Logβ₁₁₁ = 14.1 Logβ₂ = 20.5 Logβ₁₂₂ = 27.9pCu²⁺ = 9.9 Logβ₁₂₁ = 23.0 Logβ₁₂₀ = 17.3 pCu²⁺ = 7.7 Zn²⁺ chelation^(a)Logβ₁ = 8.1 Logβ₁₁₁ = 13.1 Logβ₂ = 15.0 Logβ₁₂₁ = 19.6 pZn²⁺ = 6.3Logβ₁₂₀ = 13.2 pZn²⁺ = 6.0 Fe³⁺ chelation^(b) pKa₁ = 9.92 pFe³⁺ = 23.4pKa₂ = 3.55 Logβ₁₁₀ = 14.85 Logβ₁₂₀ = 27.25 Logβ₁₃₀ = 37.24 pFe³⁺ = 20.2^(a)Except for Fe³⁺, the pKas and log β values were determined in 0.1 Maqueous NaCl/MeOH, 1/1, v/v, mixture. ^(b)For Fe³⁺, the pKas and log βvalues were determined in 0.1 M aqueous NaCl. For details, see Example29B

A utility of compounds of this invention may be in the treatment ofpatients with kidney disease in which the presence of iron is detectedin the urine. The detection of both protein content and free iron inurine as a possible method of monitoring kidney disease has beenreported in U.S. Pat. No. 6,906,052.

One biological function of the kidney is to retain protein. The term“proteinuria” means the presence of an excess of serum proteins in theurine, and may be a sign of renal (kidney) damage. Injury to theglomerulus or tubule or pancreas can adversely affect the ability of thekidney to retain protein. In the urine of animals with nephriticsyndrome, the pH of the urine can vary from pH 5.2 to 7.8. Animalexperiments have shown that iron is bound to transferrin at a pH of6.05. When the pH drops to below 6.0, there is a marked increase inunbound iron. Iron dissociated from transferrin is able to causepotentially serious free radical damage to the kidney. Small lowmolecular chelator such as deferiprone has been used to chelate the freeiron as a possible treatment therapy.

Cooper et al. reported the urinary iron speciation (American Journal ofKidney Diseases, 25, 1995, 314-319) in nephrotic syndrome where iron ispresented to the tubule fluid in a nonreactive form in association withtransferrin as a result of the glomerular protein leak. In nephriticrats, iron remains bound to transferrin throughout the nephron and isexcreted as such in the urine at alkaline pH. As urine pH decreasesbelow 6, iron starts to dissociate from transferrin. As mentionedearlier, free iron is redox active and may cause further progression ofthe renal diseases.

A weak base compound can accumulate at an acidic compartment to exertits biological action. Neutral compounds and strong bases do notaccumulate in such a manner. For example, the antisecretory agentomeprazole is a weak base that concentrates in the acidic compartment ofthe parietal cell to exert its pharmacological properties. The aminoderivatives of 3-hydroxypyridin-4-one of this invention favor theaccumulation at sites wherein the compartment is slightly acidic. Onesuch example may be the nephron of kidney disease patients.

The amino derivatives of 3-hydroxypyridin-4-one of this invention haveat least one of a number of properties: (a) they are weak amines thatcan accumulate in the acidic compartment of a biological system; (b) the1:3 FeL₃ chelates are stable at lower pH between 5 and 7.2 when comparedto the chelate from the neutral alkyl derivatives of3-hydroxypyridin-4-one such as deferiprone; (c) they are non-redoxactive as evidenced by the cyclic voltammetric study; (d) they carry abulky substituent at the C2 or C5 position that may block theglucuronidation of the C3-OH, and may thus require a lower therapeuticdose of drug; (e) higher clearance rate than deferiprone in cassettedosing pharmacokinetic studies. Thus compounds of this invention mayhave a propensity to undergo urinary excretion, and it is understoodthat the relevant site of free iron for renal disease patients is thekidney.

Another possible utility of the amino compounds of this invention is inthe treatment of cancer and inflammatory lung disorders. Buss et al.reviewed the role of iron chelation in cancer therapy (Current MedicinalChemistry, 2003, 12, 1021-1034). DNA damage after oxidative stressinvolves a transition metal such as iron. Lysosomes contain acomparatively high concentration of redox-active iron, which is mainlygenerated from the degradation of iron-containing proteins. The acidiccompartment of the lysosome further facilitates iron catalysed oxidativereactions (Kurz et al., Biochem. J. (2004) 378, 1039-1045). The ironchelator DFO has been reported to inhibit DNA synthesis and cellproliferation. DFO is a weak base with a free amino terminal and canaccumulate in the lysosome to exert its chelation mechanism.Unfortunately, DFO is a large peptide hexadentate chelator and will noteasily penetrate the cell. The amine compounds of this invention are lowmolecular weight compounds. The weak basic nature of the compound andits lipophilic character allows the compound to accumulate in the acidiccompartment of the lysosomes.

Richardson et al. reported that the most important cellular pool ofredox-active iron may exist within lysosomes, making the organellesvulnerable to oxidative stress (Expert Opinion on Investigational Drugs,August 2005, Vol. 14, No. 8, Pages 997-1008). Oxidative stress willresult in tissue damage. As a result, iron-chelating therapy thattargets the lysosome may be a possible treatment strategy forinflammatory pulmonary diseases. Weak base cell-permeable low molecularweight iron chelators may accumulate in the acidic compartment oflysosomes, and may therefore be more effective than desferrioxamine ascytoprotective agents. Therefore, another possible utility for the weakbases of this invention is the use of such compounds for the treatmentof inflammatory pulmonary diseases.

Most of the non-amino N¹-trifluoroethyl or C²-difluoroethyl derivativesof 3-hydroxypyridin-4-one of this invention are intermediates for thesynthesis of the amino derivatives. In addition, compounds of formula Iwherein G¹ is C₁-C₆ alkyl and G² is trifluoroethyl or G¹ isdifluoroethyl and G² is C₁-C₆ alkyl are examples of derivatives of3-hydroxypyridin-4-ones without an amine side chain. Some of theseneutral derivatives of 3-hydroxypyridin-4-one of this invention aresignificantly more lipophilic than deferiprone. In BBB cassette dosingstudies, they display higher brain to plasma concentration ratio, makingthem more favorable for accumulation in the brain. These compounds maybe targeted for accumulation in the brain and used towards treatment ofdiseases such as Friedreich's ataxia wherein the chelator is used toreduce ataxia and cerebellar iron in the brain.

All compounds of this invention have specificity for the complexation ofFe(III) with favorable phenolic C3 OH pKas and pFe(III)>19, a smooth 1:3ferric chelate formation as evident by Job's plot, and a D_(7.4)value>0.1. Further, the metal selectivity studies show that the compounddoes not chelate essential metals such as calcium, magnesium and zinc.

Although various embodiments of the invention are disclosed herein, manyadaptations and modifications may be made within the scope of theinvention in accordance with the common general knowledge of thoseskilled in this art. Such modifications include the substitution ofknown equivalents for any aspect of the invention in order to achievethe same result in substantially the same way. Numeric ranges areinclusive of the numbers defining the range. The word “comprising” isused herein as an open-ended term, substantially equivalent to thephrase “including, but not limited to”, and the word “comprises” has acorresponding meaning. As used herein, the singular forms “a”, “an” and“the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a thing” includes more thanone such thing. Citation of references herein is not an admission thatsuch references are prior art to the present invention. Any prioritydocument(s) are incorporated herein by reference as if each individualpriority document were specifically and individually indicated to beincorporated by reference herein and as though fully set forth herein.The invention includes all embodiments and variations substantially ashereinbefore described and with reference to the examples and drawings.

Various alternative embodiments and examples of the invention aredescribed herein. These embodiments and examples are illustrative andshould not be construed as limiting the scope of the invention.

Example 1 Preparation of3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) Preparation of3-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one.

3-(Benzyloxy)-2-methyl-4H-pyran-4-one (1.00 g, 4.6 mmol) was mixed withtrifluoroethylamine hydrochloride (1.35 g, 10.0 mmol) in pyridine (10mL). The reaction mixture was heated in a sealed flask at 75° C. for 5hours. The mixture was concentrated and the residue was purified bycolumn chromatography on silica gel with 5% methanol in ethyl acetate aseluant to give3-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.82mg) as beige solid. Yield=60%; ¹H NMR (CDCl₃, 90 MHz) δ (ppm): 7.02-7.58(m, 6H), 6.42 (d, J=7.5 Hz, 1H), 5.20 (s, 2H), 4.30 (q, J=8.3 Hz, 2H)and 2.10 (s, 3H).

(b) Preparation of3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one.

3-(Benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (820mg, 2.8 mmol) was mixed with 10% palladium on charcoal (wet, 84 mg) inmethanol (20 mL). The mixture was stirred at room temperature underhydrogen at 30 psi in a Parr apparatus for 35 minutes. The mixture wasfiltered through Celite™ and the filtrate was concentrated. The residuewas triturated with ether to give3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (511 mg) asoff-white solid. Yield=89%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 7.60 (d,J=7.4 Hz, 1H), 6.20 (d, J=7.4 Hz, 1H), 4.99 (q, J=8.8 Hz, 2H) and 2.29(s, 3H).

Example 2 Preparation of3-hydroxy-2-ethyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) In a similar manner as in example 1(a),3-(benzyloxy)-2-ethyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (1.10 g)was prepared from 3-(benzyloxy)-2-ethyl-4H-pyran-4-one (1.20 g, 5.2mmol) and 2,2,2,-trifluoroethylamine hydrochloride (3.57 g, 26.1 mmol)in pyridine (10 mL). Yield=67%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm):7.07-7.59 (m, 6H), 6.51 (d, J=7.7 Hz, 1H), 5.20 (s, 2H), 4.38 (q, J=7.7Hz, 2H), 2.58 (q, J=7.5 Hz, 2H) and 0.97 (t, J=7.5 Hz, 3H); MS m/z 312[M+1]⁺.

(b) In a similar manner as described in example 1(b),2-ethyl-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.30g) wasprepared from3-(benzyloxy)-2-ethyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.90g,2.9 mmol) with 10% palladium on charcoal (wet, 90 mg) in methanol (5 mL)and ethanol (35 mL) under hydrogen at 15 psi for 1.5 hours. Yield=47%;¹H NMR (DMSO-D₆, 400 MHz) δ (ppm): 7.58 (d, J=7.3 Hz, 1H), 6.41 (d,J=7.3 Hz, 1H), 4.92 (q, J=8.1, 2H), 2.72 (t, J=7.5 Hz, 2H) and 1.20 (t,J=7.5 Hz, 3H); MS m/z 222 [M+1]⁺.

Example 3 Preparation of1-(2,2-difluoroethyl)-3-hydroxy-2-methylpyridin-4(1H)-one

(a) Preparation of3-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one.

3-(Benzyloxy)-2-methyl-4H-pyran-4-one (432 mg, 2.0 mmol) was mixed with2,2-difluoroethylamine (655 mg, 8.0 mmol) and triethylaminehydrochloride (1.10 g, 8.0 mmol) in pyridine (6 mL) in a sealed vial.The reaction mixture was heated at 110° C. for overnight. The solid wasfiltered and washed with ethyl acetate. The filtrate was concentratedunder reduced pressure and the residue was mixed with water, and thenextracted with ethyl acetate. The organic layer was washed with waterand brine. The product was purified by column chromatography on silicagel with 5% methanol in ethyl acetate as eluant to give3-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (337 mg)as pale-yellow solid. Yield=60%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.66(d, J=7.1 Hz, 1H), 7.16-7.55 (m, 5H), 6.46 (d, J=7.1 Hz, 1H), 5.55 (t,J=55.0 Hz, 1H), 4.45 (t, J=14.8 Hz, 1H) and 2.20 (s, 3H); MS m/z 280[M+1]⁺.

(b) In a similar manner as example 1(b),1-(2,2-difluoroethyl)-3-hydroxy-2-methylpyridin-4(1H)-one (160 mg) wasprepared from3-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (337 mg,1.2 mmol) with 10% Pd/C (wet, 90 mg) in methanol under 1 atmosphere ofhydrogen using a balloon for 5 minutes. Yield=70%; ¹H NMR (MeOD-D₄, 90MHz) δ (ppm): 7.60 (d, J=7.3 Hz, 1H), 6.39 (d, J=7.3 Hz, 1H), 6.23 (tt,J=54.0, 2.9 Hz, 1H), 4.51 (td, J=14.8, 2.9 Hz, 2H) and 2.43 (s, 3H); MSm/z 190 [M+1]⁺.

Example 4 Preparation of5-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) Preparation of5-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one.

5-(Benzyloxy)-2-methyl-4H-pyran-4-one (4.32 g, 20.0 mmol) was mixed withtrifluoroethylamine (6.92 g, 70.0 mmol) in 6N HCl (11.7 mL) and ethanol(5.8 mL). The reaction mixture was heated in a sealed flask at 100° C.for 20 hours. The mixture was then concentrated in vacuo and the residuewas diluted with water. The solid was filtered, washed with water andether to give5-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (5.01g) as white solid. Yield=84%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.99 (s,1H), 7.14-7.65 (m, 5H), 6.80 (s, 1H), 4.91-5.25 (m, 4H), 2.53 (s, 3H).

(b) 5-(Benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(45.8 g, 164 mmol) was mixed with 6N HCl (100 mL) and isopropanol (20mL). The mixture was heated at 110° C. oil bath for 8 hours and thenconcentrated by rotary evaporator. The residue was triturated withacetone and ether to give5-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-onehydrochloride (24.5 g). Yield=65%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm):8.18 (s, 1H), 7.21 (s, 1H), 5.31 (q, J=8.2 Hz, 2H) and 2.67 (s, 3H).

Example 5 Preparation of1-(2,2-difluoroethyl)-5-hydroxy-2-methylpyridin-4(1H)-one

(a) In a similar manner as described in example 4(a),5-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (2.20 g)was prepared from a mixture of 5-(benzyloxy)-2-methyl-4H-pyran-4-one(3.00 g, 13.8 mmol), difluoroethylamine (2.48 g, 55.2 mmol),triethylamine hydrochloride (5.58 g, 55.2 mmol) and pyridine (15 mL).Yield=58%; ¹H NMR (90 MHz, MeOD-D₄) δ (ppm): 7.53 (s, 1H), 7.27-7.45 (m,5H), 6.36 (s, 1H), 5.56-6.77 (tt, J=54.9, 3.6 Hz, 1H), 5.04 (s, 2H),4.24-4.60 (td, J=14.9, 2.7, 2H) and 2.36 (s, 3H); MS m/z 280 [M+1]⁺.

(b) In a similar manner as described in example 1(b),1-(2,2-difluoroethyl)-5-hydroxy-2-methylpyridin-4(1H)-one (230 mg) wasprepared from5-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (500 mg,1.80 mmol) with 10% Pd/C (wet, 50 mg) in methanol (40 mL) under hydrogenat 15 psi pressure in a Parr apparatus for 27 minutes. Yield=99%; ¹H NMR(MeOD-D₄, 90 MHz) δ (ppm): 7.46 (s, 1H), 6.37 (s, 1H), 5.62-6.83 (tt,J=54.9, 3.6 Hz, 1H), 4.26-4.60 (td, J=15.3, 2.4 Hz, 2H) and 2.38 (s,3H); MS m/z 190 [M+1]⁺.

Example 6 Preparation of3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) 5-(Benzyloxy)-4-oxo-4H-pyran-2-carboxylic acid (10.5 g, 42.7 mmol)was dissolved in sodium hydroxide solution (1.71 g, 42.7 mmol in 77 mLde-ionized water). 2,2,2-Trifluoroethylamine hydrochloride (23.1 g, 171mmol) was added and the resulting suspension was stirred at 70° C.(oil-bath temperature) in the sealed flask for 17 hours. The reactionmixture was then filtered and the off-white solid was washed withde-ionized water (20 mL×5) to give5-(benzyloxy)-4-oxo-1-(2,2,2-trifluoroethyl)-1,4-dihydropyridine-2-carboxylicacid (6.00 g). Yield=43%; ¹H NMR (MeOD-D₄, 90 MHz) δ 7.30 (s, 1H),6.76-7.09 (m, 5H), 6.71 (s, 1H), 4.93 (d, J=8.4 Hz, 2H) and 4.65 (s,2H); MS m/z 328 [M+1]⁺.(b)5-(Benzyloxy)-4-oxo-1-(2,2,2-trifluoroethyl)-1,4-dihydropyridine-2-carboxylicacid (4.70 g, 14.4 mmol) was mixed with DMF (25 mL) and heated to 130°C. (bath temperature) for 3 hours. The mixture was concentrated underreduced pressure using a rotary evaporator and the residue was mixedwith ethyl acetate (50 mL). It was then stirred for 2 hours at roomtemperature and filtered. The filtrate was concentrated to give3-(benzyloxy)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (3.58 g).Yield=69%; ¹H NMR (DMSO-D₆, 400 MHz) δ (ppm) 7.57-7.84 (m, 2H),7.22-7.57 (m, 5H), 6.25 (br. s, 1H) and 4.69-5.28 (m, 4H); MS m/z 284[M+1]⁺.(c) 3-(Benzyloxy)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (1.2 g, 4.2mmol) was mixed with 10% Palladium on charcoal (wet, 0.12 g) in ethanol(70 mL). The resulting mixture was hydrogenated at 15 psi of hydrogenpressure for 1.5 hours. Palladium was removed by filtration through alayer of Celite™ and the Celite™ cake was washed with methanol (5 mL×3).The filtrate was evaporated to give3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.78 g) as whitesolid. Yield=95%; ¹H NMR (DMSO-D₆, 400 MHz) δ (ppm) 7.60 (d, J=7.1 Hz,1H), 7.46 (s, 1H), 6.23 (d, J=7.1 Hz, 1H) and 4.80-5.00 (m, 2H); MS m/z194 [M+1]⁺.

Example 7 Preparation of3-hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

5-Hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-onehydrochloride (4.87 g. 20.0 mmol) was mixed with 37% formaldehyde (30mL) and 6N sodium hydroxide (7 mL, 42.0 mmol). The reaction mixture wasstirred at 39-42° C. for 11 hours, and then additional 37% formaldehyde(30 mL) was added. The reaction mixture was stirred at 37° C. for 12hours and then left at room temperature for a further 12 hours. Thesolid was filtered and the filtrate was acidified to pH about 5 to 6.The solution was concentrated with silica gel and the product waspurified by column chromatography with a gradient mixture of 5-10%methanol in ethyl acetate as eluant to give the title compound3-hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(3.02 g) as pale-peach solid. Yield 63.5%; ¹H NMR (DMSO-D₆+D₂O, 90 MHz)δ (ppm): 6.20 (s, 1H), 5.15 (q, J=8.8 Hz, 2H), 4.33-4.92 (m, 2H) and2.37 (s, 3H); MS m/z 238 [M+1]⁺.

Example 8 A. Preparation of2-[(dimethylamino)methyl]-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

5-Hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-onehydrochloride (415 mg, 1.7 mmol) was mixed withN,N,N′,N′-tetramethylmethanediamine (4 mL) in ethanol (10 mL) and heatedat 80° C. for 21 hours. The reaction mixture was concentrated by rotaryevaporator and the residue was triturated with water to give2-[(dimethylamino)methyl]-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(315 mg) as white solid. Yield=70%; ¹H NMR (DMSO-D₆+D₂O, 90 MHz) δ(ppm): 6.20 (s, 1H), 5.15 (q, J=8.8 Hz, 2H), 4.69 (br. s, 2H) and 2.37(s, 3H); MS m/z 265 [M+1]⁺.

B. Preparation of2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

In a similar manner,2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(0.21 g) was prepared from3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.60g, 3.1 mmol)reacted with N,N,N′,N′-tetramethyldiaminomethane (8.50 mL, 62.2 mmol) inethanol (10 mL) at 75° C. for 20 hours. Yield=27%; ¹H NMR (MeOD-D₄, 90MHz) δ (ppm): 7.81 (d, J=7.5 Hz, 1H), 6.52 (d, J=7.5 Hz, 1H), 5.07 (d,J=8.0 Hz, 2H), 4.60 (s, 2H) and 2.94 (s, 6H); MS m/z 251 [M+1]⁺.

C. Preparation of1-(2,2-difluoroethyl)-2-[(dimethylamino)methyl]-3-hydroxy-6-methylpyridin-4(1H)-one

In a similar manner,1-(2,2-difluoroethyl)-2-[(dimethylamino)methyl]-3-hydroxy-6-methylpyridin-4(1H)-one(0.41 g) was prepared from1-(2,2-difluoroethyl)-5-hydroxy-2-methylpyridin-4(1H)-one (0.40 g, 2.1mmol) and N,N,N′,N′-tetramethyldiaminomethane (4.3 mL, 31.7 mmol) inethanol (10 mL) at 75° C. for 19 h. Yield=78%; ¹H NMR (DMSO-D₆, 90 MHz)δ ppm: 6.45 (tt, J=55.1, 3.5 Hz, 1H), 6.24 (s, 1H), 4.74 (td, J=14.6,3.5 Hz, 2H), 3.55 (s, 2H), 2.37 (s, 3H), 2.17 (s, 6H); MS m/z 247[M+1]⁺.

Example 9 Preparation of 3-hydroxy-6-methyl-2-(piperidin-1-ylmethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

3-Hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(375 mg, 1.6 mmol) was mixed with acetonitrile at 80° C. and the thionylchloride (753 mg, 6.3 mmol) was added. The reaction mixture was stirredfor 5 minutes and then concentrated by rotary evaporator to give2-(chloromethyl)-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-onehydrochloride. The chloride compound was added to a solution ofpiperidine (672 mg, 7.9 mmol) in isopropanol (5 mL) at room temperature.Five minutes later, the reaction mixture was diluted with water andextracted with ethyl acetate. The organic layer was washed with watertwice and brine, dried and concentrated. The residue was triturated withether/hexanes to give3-hydroxy-6-methyl-2-(piperidin-1-ylmethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(165 mg) as pale orange solid. Yield=34%; ¹H NMR (MeOD-D₄, 90 MHz) δ(ppm): 6.37 (s, 1H), 3.72 (br. s, 2H), 2.45 (br. m, 7H) and 1.51 (br. m,6H); MS m/z 305 [M+1]⁺.

Example 10 Preparation ofN-methyl-N2-[2,2,2-trifluoro-1-(3-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)ethyl]-D-alaninamideandN-methyl-N2-[2,2,2-trifluoro-1-(3-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)ethyl]-L-alaninamide(Apo6998 and Apo6999)

To a solution of 3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride(100.0 g, 0.62 mol) dissolved in a solution of 6N NaOH (206.9 mL) atice-water bath was added trifluoroacetaldehyde methyl hemiacetal (131.9mL, 1.24 mmol). The resulting solution was heated to 95° C. forovernight. The reaction mixture was then cooled, and at ice-water baththe pH of the mixture was adjusted to about 5 using a 6N HCl solution.The precipitated solid was collected by filtration, and the solid wasthoroughly washed with de-ionized water (100 mL×2), and then dried undervacuum at 43° C. for overnight to afford3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(94.8 g) as a white solid. Yield=68% yield; ¹H NMR (90 MHz, MeOD-D₄) δ(ppm): 7.60 (d, J=7.1 Hz, 1H), 6.40 (d, J=7.2 Hz, 1H), 5.92 (q, J=8.2Hz, 1H), 3.98 (s, 3H); MS m/z 224 [M+1], 158 (100%).

To an ice cooled suspension of3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.60 g, 7.2 mmol) in 50 mL of acetonitrile was added dropwise SOCl₂(0.80 mL, 10.8 mmol) followed by pyridine (0.6 mL, 7.2 mmol). Theresulting suspension was stirred for 0.5h and then refluxed for 2h. Thereaction mixture was evaporated to dryness. To a suspension of theresidue in 10 mL of acetonitrile was added a suspension ofL-H-Ala-NHMe.HCl (1.19 g, 8.6 mmol) and Et₃N (4.0 mL, 28.7 mmol) in 20mL of acetonitrile. The resulting mixture was stirred at RT forovernight. The reaction mixture was evaporated to dryness, and theresidue was purified by flash chromatography on silica gel (10% concNH₄OH in IPA as eluant) to afford 2.20 g of the two diastereoisomers,Apo6998 and Apo6999. A sample of each diastereoisomers was obtainedthrough further purification by Biotage using reverse phase C18cartridge.

More polar isomer by HPLC (Rt=3.43 min) (110 mg). ¹H NMR (400 MHz,MeOD-D₄) δ (ppm): 7.68 (d, J=7.1 Hz, 1H), 6.41 (d, J=7.1 Hz, 1H),4.68-4.80 (m, 1H), 3.83 (s, 3H), 3.41-3.56 (m, 1H), 2.57 (s, 3H), 1.30(d, J=6.1 Hz, 3H); MS m/z 330 [M+Na]⁺, 308 [M+1]⁺, 126 (100%).

Less polar isomer by HPLC (Rt=3.68 min) (100 mg). ¹H NMR (400 MHz,MeOD-D₄) δ (ppm): 7.70 (d, J=7.1 Hz, 1H), 6.44 (d, J=7.1 Hz, 1H),4.60-4.70 (m, 1H), 3.79 (s., 3H), 3.20-3.24 (m, 1H), 2.75 (s, 3H), 1.28(d, J=6.1 Hz, 3H); MS m/z 330 [M+Na]⁺, 308 [M+1]⁺, 126 (100%).

HPLC condition: Column: Symmetry C18, 5 μm; 3.9 mm×150 mm; Flow rate:1.0 mL/min; Mobile phase: A=0.035% HClO₄, B=Acetonitrile; Gradient(min-B %): 0-10, 10-100, 12-100, 14-50.

Example 11 Preparation of2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one(Apo7041)

To a suspension of3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(5.00 g, 22.4 mmol) in 40 mL of acetonitrile at ice-water bath was addedVilsmeier's reagent (4.30 g, 33.6 mmol) portionwise. The resultingmixture was stirred for 2h before being added to a suspension ofdimethylamine hydrochloride (6.00 g, 73.6 mmol) and Et₃N (15.0 mL, 107.6mmol) in 30 mL of acetonitrile. The resulting suspension was stirred atRT for overnight. The solid was filtered off and the filtrate wasconcentrated to dryness. The residue was purified by flashchromatography on silica gel (10% MeOH in EtOAc as eluant) to affordtitle compound, Apo7041 (1.8 g). Yield=32%; ¹H NMR (90 MHz, CD₃OD-D₄) δ(ppm): 7.63 (d, J=7.3 Hz, 1H), 6.41 (d, J=7.3 Hz, 1H), 4.78 (q, J=8.1Hz, 1H), 3.99 (s, 3H), 2.41 (s, 6H); MS m/z 273 [M+Na]⁺, 251 [M+1]⁺, 206(100%).

Example 12 A. Preparation of3-hydroxy-1-methyl-2-{2,2,2-trifluoro-1-[methyl(prop-2-yn-1-yl)amino]ethyl}pyridin-4(1H)-one(Apo7057)

To 20 mL acetonitrile cooled in an ice-water bath was added DMF (0.42mL, 5.4 mmol) followed by oxalyl chloride (0.47 mL, 5.4 mmol) dropwise.To this resulting suspension was added3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.0 g, 4.5 mmol) in one portion. The mixture was then stirred for 2h.Then, Et₃N (2.50 mL, 17.9 mmol) was added to this reaction mixturefollowed by N-methyl propargylamine (0.75 mL, 9.0 mmol). The reactionmixture was stirred at RT for overnight. The solid was filtered off, andthe filtrate was concentrated to dryness. The residue was purified byflash chromatography on silica gel (5% MeOH in CH₂Cl₂ as eluant) toafford the title compound, Apo7057 (570 mg) as an orange powder.Yield=46.4%; ¹H NMR (400 MHz, DMSO+a few drops of D₂O) δ (ppm): 7.6 (br.s., 1H), 6.25 (d, J=7.1 Hz, 1H), 5.15 (br. s., 1H), 3.87 (s, 3H),3.37-3.67 (m, 2H), 3.23 (br. s., 1H), 2.32 (br. s., 3H); MS m/z 275[M+1]⁺, 206 (100%).

B. Preparation of3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one(Apo7058)

In a similar manner, Apo7058 was prepared from3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.0 g, 4.5 mmol) and piperidine (0.88 mL, 8.9 mmol). The title compoundApo7058 (700 mg) was obtained as a white solid after purification byflash chromatography (4% MeOH in CH₂Cl₂ as eluant). Yield=54%; ¹H NMR(400 MHz, DMSO-D6, 75° C.) δ (ppm): 7.59 (d, J=6.8 Hz, 1H), 6.19 (d,J=6.8 Hz, 1H), 4.82 (q, J=9.0 Hz, 1H), 3.88 (s, 3H), 2.46-2.84 (m, 4H),1.29-1.74 (m, 6H) MS m/z 291 [M+1]⁺, 206 (100%).

C. Preparation of3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridin-4(1H)-one(Apo7073)

In a similar manner, Apo7073 was prepared from3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.0 g, 4.5 mmol) and 1-methylpiperazine (1.0 mL, 9.0 mmol). The titlecompound Apo7073 (401 mg) was obtained after purification by Biotagereverse C18 column. Yield=29%; ¹H NMR (400 MHz, DMSO-d6, 75° C.) δ(ppm): 7.63 (d, J=6.8 Hz, 1H), 6.21 (d, J=7.4 Hz, 1H), 4.94 (q, J=8.5Hz, 1H), 3.86 (s, 3H), 3.05 (br. s., 4H), 2.92 (br. s., 4H), 2.64 (s,3H); MS m/z 306 [M+1]⁺, 206 (100%).

D. Preparation of2-[1-(cyclopropylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one(Apo7074)

In a similar manner, Apo7074 was prepared from3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.0 g, 4.5 mmol) and cyclopropylamine (0.62 mL, 9.0 mmol). The titlecompound Apo7074 (470 mg) was obtained after purification by flashchromatography (5% MeOH in CH₂Cl₂ as eluant). Yield=40%; ¹H NMR (400MHz, DMSO+a few drops of D₂O) δ (ppm): 7.67 (d, J=6.8 Hz, 1H), 6.25 (d,J=7.1 Hz, 1H), 4.70 (q, J=8.1 Hz, 1H), 3.74 (s, 3H), 2.04 (br. s., 1H),0.34-0.43 (m, 4H); MS m/z 263 [M+1]⁺, 206 (100%).

E. Preparation of3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(prop-2-en-1-ylamino)ethyl]pyridin-4(1H)-one(Apo7075)

In a similar manner, Apo7075 was prepared from3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.0 g, 4.5 mmol) and allylamine (0.67 mL, 9.0 mmol). The title compoundApo7075 (497 mg) was obtained after purification by flash chromatography(5% MeOH in CH₂Cl₂ as eluant). Yield=42%; ¹H NMR (400 MHz, DMSO+a fewdrops of D₂O) δ (ppm): 7.65 (d, J=7.1 Hz, 1H), 6.24 (d, J=7.4 Hz, 1H),5.70-5.80 (m, 1H), 5.14 (d, J=17.4 Hz, 1H), 5.06 (d, J=10.1 Hz, 1H),4.63 (q, J=8.2 Hz, 1H), 3.67 (s, 3H), 3.15-3.19 (m, 2H); MS m/z 263[M+1]⁺, 206 (100%).

Example 13 A. Preparation of5-(benzyloxy)-3-chloro-2-methylpyridin-4(1H)-one

To a solution of 5-(benzyloxy)-2-methylpyridin-4(1H)-one (9.00 g, 41.8mmol) in 2M sodium hydroxide (62.5 mL, 125 mmol) under ice-water bath, asolution of 10-14% sodium hypochlorite (62.5 mL) was added slowly during20 minutes. The reaction mixture was stirred at room temperature foranother hour. The reaction mixture was carefully neutralized with 6N HClto pH about 7 with external cooling to keep the internal temperaturebelow 25° C. The solid was filtered and washed with water (3×), thendried in a vacuum oven for overnight. Thus,5-(benzyloxy)-3-chloro-2-methylpyridin-4(1H)-one (9.03 g) was obtainedas a white solid. Yield=86%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 11.74(br. s, 1H), 7.14-7.68 (m, 6H), 5.02 (s, 2H) and 2.33 (s, 3H).

B. Preparation of5-(benzyloxy)-3-chloro-2-(hydroxymethyl)pyridin-4(1H)-one

In a similar manner,5-(benzyloxy)-3-chloro-2-(hydroxymethyl)pyridin-4(1H)-one (10.50 g) wasprepared from 5-(benzyloxy)-2-(hydroxymethyl)pyridin-4(1H)-one (11.56 g,50 mmol) and a solution of 10-14% sodium hypochlorite (75 mL) in 2Msodium hydroxide (75 mL) solution. Yield=81%; ¹H NMR (DMSO-D₆, 90 MHz) δ(ppm): 11.35 (br. s, 1H), 7.05-7.66 (m, 6H), 5.79-6.32 (m, 1H), 5.03 (s,2H) and 4.54 (s, 2H).

C. Preparation of 5-(benzyloxy)-3-chloro-1,2-dimethylpyridin-4(1H)-one

5-(Benzyloxy)-3-chloro-2-methylpyridin-4(1H)-one (3.00 g, 12.0 mmol) wassuspended in 25 mL of DMF. Potassium carbonate (3.30 g, 24.0 mmol) wasadded followed by the addition of iodomethane (1.53 mL, 24.0 mmol). Theprogress of the reaction was monitored by TLC (30% ethyl acetate inhexanes). Upon completion, the reaction was allowed to stir at roomtemperature. Water was added and a white precipitate formed. The solidwas collected by suction filtration, allowed to air dry and then furtherdried under vacuum. Thus,5-(benzyloxy)-3-chloro-1,2-dimethylpyridin-4(1H)-one (2.00 g) wasobtained. Yield=63%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.61 (s, 1H),7.27-7.46 (m, 5H), 5.21 (s, 2H), 3.75 (s, 3H) and 2.54 (s, 3H).

D. Preparation of5-(benzyloxy)-3-chloro-2-(hydroxymethyl)-1-methylpyridin-4(1H)-one

In a similar manner,5-(benzyloxy)-3-chloro-2-(hydroxymethyl)-1-methylpyridin-4(1H)-one (7.52g) was prepared from5-(benzyloxy)-3-chloro-2-(hydroxymethyl)pyridin-4(1H)-one (10.0 g, 37.6mmol), iodomethane (10.7 g, 75.2 mmol) and potassium carbonate (10.3 g,75.2 mmol) in DMF (50 mL). Yield=72%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm):7.77 (s, 1H), 7.17-7.58 (m, 5H), 5.65 (br. s, 1H), 5.04 (s, 2H), 4.70(br. s, 2H) and 3.81 (s, 3H).

E. Preparation of5-(benzyloxy)-3-chloro-1-methyl-4-oxo-1,4-dihydropyridine-2-carboxylicacid

To a mixture of5-(benzyloxy)-3-chloro-2-(hydroxymethyl)-1-methylpyridin-4(1H)-one (4.90g, 17.5 mmol), TEMPO (120 mg, 0.77 mmol) and potassium bromide (120 mg,1.00 mmol) in acetone (50 mL) and saturated sodium bicarbonate (40 mL)below 7° C. was added dropwise a 10-14% sodium hypochlorite (50 mL)solution during 30 minutes. After being stirred for 2 hours, thereaction mixture was diluted with water and adjusted to pH about 1.5with 6N HCl. The solid was filtered and washed with water to give5-(benzyloxy)-3-chloro-1-methyl-4-oxo-1,4-dihydropyridine-2-carboxylicacid (2.89 g) as a white solid. Yield=56%; ¹H NMR (DMSO-D₆, 90 MHz) δ(ppm): 7.79 (s, 1H), 7.16-7.62 (m, 5H), 5.03 (s, 2H) and 3.67 (s, 3H);MS m/z 294 [M+1]⁺.

F. Preparation of 3-(benzyloxy)-5-chloro-1-methylpyridin-4(1H)-one

5-(Benzyloxy)-3-chloro-1-methyl-4-oxo-1,4-dihydropyridine-2-carboxylicacid (3.50 g, 11.9 mmol) was heated in DMF (10 mL) for one hour. Thereaction mixture was concentrated by rotary evaporation and the residuewas triturated with ethyl acetate/ether to give3-(benzyloxy)-5-chloro-1-methylpyridin-4(1H)-one (2.80 g) as a palebrown solid. Yield=94%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 8.08 (d, J=1.8Hz, 1H), 7.68 (d, J=1.8 Hz, 1H), 7.19-7.58 (m, 5H), 5.01 (s, 2H) and3.67 (s, 3H).

Example 14 A. Preparation of3-chloro-5-hydroxy-1-methylpyridin-4(1H)-one

3-(Benzyloxy)-5-chloro-1-methylpyridin-4(1H)-one (2.70 g, 10.8 mmol) wasmixed in 6N HCl (15 mL) and ethanol (10 mL). After being refluxed for 2hours, the reaction mixture was concentrated by rotary evaporator. Theresidue was mixed with water (5 mL) and basified to pH 8-9 withconcentrated ammonia. An off-white precipitate came out, ant the mixturewas again concentrated in vacuo to remove volatiles. The off-white solidwas collected by suction filtration and dried to give3-chloro-5-hydroxy-1-methylpyridin-4(1H)-one (1.32 g). Yield=76.6%; ¹HNMR (DMSO-D₆, 90 MHz) δ (ppm): 7.98 (s, 1H), 7.47 (s, 1H) and 3.67 (s,3H).

B. Preparation of 3-chloro-5-hydroxy-1,2-dimethylpyridin-4(1H)-one

In a similar manner, 3-chloro-5-hydroxy-1,2-dimethylpyridin-4(1H)-one(600 mg), was prepared by refluxing a mixture of5-(benzyloxy)-3-chloro-1,2-dimethylpyridin-4(1H)-one (2.00 g, 7.6 mmol)with 6N HCl (20 mL) and methanol (10 mL) at 100° C. for 2 hours.Yield=46%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.08 (s, 1H) 4.08 (s, 3H)and 2.72 (s, 3H); MS m/z 174 [M+1]⁺.

Example 15 A. Preparation of3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one

3-Chloro-5-hydroxy-1,2-dimethylpyridin-4(1H)-one (500 mg, 2.80 mmol) wassuspended in trifluoroacetaldehyde methyl hemiacetal (3 mL). Potassiumcarbonate (119 mg, 0.86 mmol) was added and the mixture was heated to120° C. After 2.5 hours, the reaction mixture was allowed to cool toroom temperature, then diluted with methanol and filtered. The filtratewas concentrated to dryness and diluted with acetone. The solution wasfiltered and the filtrate was concentrated to give3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(650 mg) as a pink solid. Yield=85%; ¹H-NMR (MeOD-D₄, 90 MHz) δ (ppm):5.9 (q, J=9.1 Hz, 1H), 4.01 (s, 3H) and 2.65 (s, 3H); MS-ESI m/z 272[M+1]⁺.

B. Preparation of5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one

In a similar manner,5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.40 g) was prepared from 3-chloro-5-hydroxy-1-methylpyridin-4(1H)-one(1.27 g, 8.0 mmol) and trifluoroacetaldehyde methyl hemiacetal (12.7 mL)in presence of potassium carbonate (0.22 g, 1.6 mmol). Yield=68%; ¹H NMR(DMSO-D₆) δ (ppm): 8.10 (s, 1H), 5.80 (q, J=8.7 Hz, 1H) and 3.88 (s,3H); MS m/z 258 [M+1]⁺.

Example 16 A. Preparation of3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

3-Chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(300 mg, 1.10 mmol) was suspended in 10 mL of acetonitrile and thionylchloride (398 μL, 5.50 mmol) was added dropwise. The reaction wasstirred at room temperature. After 2 hours, the reaction wasconcentrated. The crude was diluted with 10 mL of methanol and sodiumborohydride (329 mg, 8.80 mmol) was added in small portions. After 15hours, the reaction was filtered and the filtrate was concentrated invacuo. The resulting solid was dissolved in methanol and ethyl acetateadded, filtered and concentrated. The crude product was purified bycolumn chromatography on silica gel using a mixture of 30% EtOAc in MeOHas eluant. Fractions rich in product were combined and evaporated todryness. The residue product was recrystallised from methanol/ethylacetate to give3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(172 mg) as a white solid. Yield=61%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm):4.1 (q, J=9.0 Hz, 2H), 3.99 (s, 3H) and 2.77 (s, 3H); MS m/z 256 [M+1]⁺.

B. Preparation of5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

In a similar manner,5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(117 mg) was prepared from5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(580 mg, 2.30 mmol). Yield=22%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.04(s, 1H), 3.91 (q, J=9.9 Hz, 2H) and 3.84 (s, 3H); MS m/z 242 [M+1]⁺.

Example 17 A. Preparation of3-chloro-6-[1-(dimethylamino)-2,2,2-trifluoroethyl]-5-hydroxy-1,2-dimethylpyridin-4(1H)-one

3-Chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(618 mg, 2.3 mmol) was mixed with pyridine (276 μL, 3.4 mmol) inacetonitrile (10 mL) at room temperature. Thionyl chloride (249 μL, 3.41mmol) was added dropwise. After being stirred at room temperature for 30minutes, the reaction mixture was concentrated by rotary evaporation.The residue was dried under vacuum and then mixed with ethanol (20 mL)under ice-water bath. An ethanolic dimethylamine (5.6 M, 4.06 mL, 22.8mmol) solution was added at about 5° C. and the mixture was stirred for20 minutes. The reaction mixture was concentrated by rotary evaporation.The residue was mixed with water (10 mL) and the pH of the solution wasadjusted to 5.5. The precipitated solid was collected by suctionfiltration, and washed with water, then triturated with ether/hexanes togive3-chloro-6-[1-(dimethylamino)-2,2,2-trifluoroethyl]-5-hydroxy-1,2-dimethylpyridin-4(1H)-one(380 mg) as an off-white solid. Yield=56%; ¹H NMR (CDCl₃, 90 MHz) δ(ppm): 4.88 (q, J=8.6 Hz, 1H), 4.08 (s, 3H), 2.65-2.81 (m, 3H) and 2.39(s, 6H); MS m/z 299 [M+1]⁺.

B. Preparation of5-chloro-2-(1-(dimethylamino)-2,2,2-trifluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one

In a similar manner,5-chloro-2-(1-(dimethylamino)-2,2,2-trifluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one(290 mg) was prepared from5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(386 mg, 1.5 mmol). Yield=68%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.04(s, 1H), 4.69-4.85 (m, 1H), 4.05 (br. s, 3H) and 2.42 (br. s, 6H); MSm/z 285 [M+1]⁺.

C. Preparation of5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-(piperidin-1-yl)ethyl)pyridin-4(1H)-one

In a similar manner,5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-(piperidin-1-yl)ethyl)pyridin-4(1H)-one(302 mg) was prepared from5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(386 mg, 1.5 mmol). Yield=60%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.03(br. s, 1H), 4.57-4.83 (m, 1H), 3.74-4.35 (m, 3H), 2.21-3.02 (m, 4H) and1.44-1.89 (m, 6H); MS m/z 325 [M+1]⁺.

Example 18 A. Preparation of2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one(Apo7078)

A sealed suspension of 3-hydroxy-1-methypyridin-4(1H)-one (1.00 g, 8.0mmol) and potassium carbonate (0.11 g, 0.8 mmol) in 2.4 mL ofdifluroacetaldehyde ethyl hemiacetal was heated to 50° C. for 18h. Thevolatile components were evaporated under reduced pressure. The residuewas dissolved in 3 mL of de-ionized water then cooled in an ice-waterbath, and the pH was adjusted to 5-6 with a 1N HCl solution. Theprecipitate was collected by suction filtration and dried. Thus, thetitle compound Apo7078 was obtained (410 mg) as a white solid.Yield=25%; ¹H NMR (400 MHz, CD₃OD) δ (ppm): 7.62 (d, J=7.1 Hz, 1H), 6.41(d, J=7.1 Hz, 1H), 6.30 (dt, ³J=55.8 Hz, ²J=5.1 Hz, 1H), 5.45 (dt,²J=5.1 Hz, ³J=11.4 Hz, 1H), 3.96 (s, 3H); MS m/z 206 [M+1]⁺, 188 (100%).

B. Preparation of2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7080)

To 10 mL of acetonitrile at ice-water bath was added DMF (0.14 mL, 1.8mmol) followed by oxalyl chloride (0.15 mL, 1.8 mmol) dropwise. To thisresulting suspension was added2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one(0.30 g, 1.5 mmol) in one portion, and the resulting mixture was stirredfor 2h. A solid was collected by filtration, and it was dissolved in 150mL of acetonitrile. To this resulting solution was added Pd/C (10%, wet,0.20 g, 66.7% w/w), and the mixture was subjected to hydrogenation under40 psi hydrogen pressure for 2h. The catalyst was filtered off, and thefiltrate was evaporated to dryness. The residue was dissolved inde-ionized water, and the pH was adjusted to 5-6 using a 6N NaOHsolution. The precipitate was collected via suction filtration to affordthe crude product (100 mg) as an off-white solid. The crude was furtherpurified by Biotage using reversed phase C18 cartridge to afford thetitle compound, Apo7080 (66 mg) as white solid. Yield=24%; ¹H NMR (400MHz, CD₃OD) δ (ppm): 7.65 (d, J=7.2 Hz, 1H), 6.41 (d, J=7.2 Hz, 1H),6.19 (tt, J=56.5, 4.7 Hz, 1H), 3.83 (s, 3H), 3.51 (dt, ³J=15.9 Hz,²J=4.6 Hz, 2H); MS m/z 190 [M+1]⁺, 188 (100%).

Example 19 Preparation ofN-2-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-N-methyl-L-alaninamide(Apo7033)

A mixture of 5-(benzyloxy)-2-(chloromethyl)-1-methylpyridin-4(1H)-onehydrochloride (7.55 g, 25.0 mmol), H-Ala-NHMe.HCl (5.14 g, 37.0 mmol)and diisopropylethylamine (12.5 mL, 72.0 mmol) in CH₃CN (50 mL) washeated at 85° C. under a nitrogen atmosphere for overnight. Volatileswere removed in vacuo, and the residue was pre-purified by columnchromatography on silica gel using a mixture of MeOH and ethyl acetateas eluant (solvent gradient of 10, 15 and 20% MeOH in ethyl acetate).The fractions rich in product were combined and evaporated to dryness.Further purification by column chromatography on silica gel using amixture of H₂O and CH₃CN (1-5% H₂O content) and then a 10% MeOH indichloromethane solution afforded(S)-2-((5-(benzyloxy)-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamide(7.17 g) in 87% yield. MS m/z 352 [M+Na]⁺, 330 (100%) [M+1]⁺, 228, 138,91.

A mixture of(S)-2-((5-(benzyloxy)-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamide(7.04 g, 21.4 mmol) and 10% Pd/C (0.90 g) in MeOH (70 mL) was subjectedto hydrogenation in a Parr apparatus at 50 psi of hydrogen pressure for2 h. The reaction mixture was filtered over celite and the filtrate wasconcentrated in vacuo. The resulting solid was dried in a vacuum oven at44° C. for overnight. Thus,(S)-2-((5-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamidewas obtained as an orange solid (4.90 g) in 96% yield. ¹H NMR (CD₃COOD)δ (ppm): 7.77 (s, 1H), 7.03 (s, 1H), 4.30-4.34 (m, 3H, OCH₂+CHCH₃), 3.98(s, 3H), 2.80 (s, 3H), 1.56 (d, J=6.3 Hz, 3H, CHCH₃); MS m/z 262[M+Na]⁺, 240 (100%) [M+1]⁺, 138, 110.

A mixture of(S)-2-((5-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamide(3.13 g, 13.1 mmol), trifluoroacetaldehyde methyl hemiacetal (3.6 mL,38.0 mmol) and potassium carbonate (2.62 g, 19.0 mmol) in CH₃CN (35 mL)was heated at 75-80° C. for overnight. Analysis of the reaction mixtureby TLC using a solvent mixture of 28-30% conc. NH₄OH in IPA as eluantindicated incomplete consumption of the starting material. A furtherportion of trifluoroacetaldehyde methyl hemiacetal (4 mL) was added, andthe mixture was heated at 95-100° C. for another 24 h. On cooling toroom temperature, the mixture was purified by column chromatography onsilica gel using a mixture of MeOH and ethyl acetate as eluant (solventgradient of 10, 15 and 20% MeOH in ethyl acetate). Thus, the titlecompoundN-2-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-N-methyl-L-alaninamide,Apo7033, was obtained as a yellowish solid (1.53 g) in 35% yield. ¹H NMR(DMSO-D₆) δ (ppm): 7.79 (t, J=4.4 Hz, 1H, NH), 6.30 (s, 1H), 5.87 (q,J=8.7 Hz, 1H, CHCF₃), 3.82 (s, 3H, NCH₃), 3.61-3.65 (dd, ²J=14.5 and⁴J=1.9 Hz, 1H, 0.5 NHCH₂), 3.47-3.52 (apparent t, J=15.2 Hz, 1H, 0.5NHCH₂), 3.08 (q, J=6.8 Hz, 1H, CHCH₃), 2.59 (d, J=4.2 Hz, 3H, NHCH₃),1.12 (dd, ²J=6.8 and ⁴J=2.3 Hz, 3H, CHCH₃); ¹³C NMR (DMSO-D₆) δ (ppm):175.0 (C═O), 169.6 (C═O), 149.2, 147.3, 125.6, 125.0 (q, J=283 Hz,CHCF₃), 113.1 (CH), 65.2 (q, J=33 Hz, CHCF₃), 56.9 (CH), 48.9 (CH₂),36.6 (NCH₃), 25.8 (NHCH₃), 19.6 (CH₃); MS m/z 360 [M+Na]⁺, 338 (100%)[M+1]⁺, 236.

Example 20N-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-L-alanine (Apo7032)

The experiment in the last step of the previous example (example 19) wasrepeated (2.9 mmol scale) except that the mixture was purified by columnchromatography on silica gel using a mixture of 28-30% conc. NH₄₀H andIPA as eluant (solvent gradient of 10, 15 and 20 and 25% NH₄₀H in IPA).In this case, the title acid compoundN-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-L-alanine(Apo7032) was obtained as an orange solid (0.7 g) in 78% yield. MS m/z347 [M+Na]⁺, 325 (100%) [M+1]⁺, 236.

Example 21 Preparation of the diastereoisomers ofN-methyl-2-[2,2,2-trifluoro-1-(5-hydroxy-6-methyl-4-oxo-1,4-dihydro-pyridin-3-yl)-ethylamino]-propionamide(Apo6884 and Apo6885)

Thionyl chloride (2.5 mL, 33.7 mmol) was added to a suspension of3-hydroxy-2-methyl-5-(2,2,2-trifluoro-1-hydroxy-ethyl)-1H-pyridin-4-one(1.50 g, 6.7 mmol) in acetonitrile (33 mL) at room temperature. Theresulting mixture was stirred for 30 min as a clear solution resulted.The progress of the reaction was monitored by TLC(methanol:dichloromethane, 1:10, v:v), which indicated consumption ofthe starting material. The reaction mixture was evaporated to dryness togive crude5-(1-chloro-2,2,2-trifluoro-ethyl)-3-hydroxy-2-methyl-1H-pyridin-4-oneas a solid.

The solid was dissolved in acetonitrile (35 mL), and H-Ala-NHMehydrochloric acid salt (1.15 g, 8.3 mmol) was added followed bytriethylamine (4.0 mL, 28.7 mmol). The heterogeneous mixture was stirredfor 60 min, while the progress of the reaction was monitored by HPLCMethod 1. HPLC analysis of the crude reaction mixture indicated thepresence of two product peaks in a ratio of about 4/3, and with RT of7.9 and 8.4 min, respectively. The reaction mixture was filtered toremove solid materials, and the filtrate was evaporated to dryness togive a solid. The solid was dissolved in ethyl acetate, and the organicsolution was extracted with a 20% ammonium chloride solution (3×40 mL).The aqueous fractions were combined (pH 6) and the pH was adjusted to 7with a NaOH solution. The aqueous solution was then extracted with ethylacetate (2×50 mL). The ethyl acetate fractions were combined andevaporated to dryness to giveN-methyl-2-[2,2,2-trifluoro-1-(5-hydroxy-6-methyl-4-oxo-1,4-dihydro-pyridin-3-yl)-ethylamino]-propionamideas a pair of diastereoisomers (850 mg, 41% yield, HPLC Method: Column:XTerra MS C18, 4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH7.4; B=Organic phase: CH₃CN; Flow rate=1.0 mL/min; Injection volume=5μL; Wavelength (λ): 220, 254, 280, 450 nm. Gradient method; min-B % 0-5,15-55, 25-55, 25.05-5, 30-5. Apo6884, RT=7.9 min, AUC=44% at λ=280 nm,and Apo6885, RT=8.4 min, AUC=35% at λ=280 nm). Samples of the twodiastereoisomers were obtained after repeated purification using theBiotage© system (C18 reverse phase cartridge; a mixture of acetonitrileand de-ionized water as eluant; gradient elution). Apo6884: 82 mg,RT=7.9 min, HPLC purity (AUC): 99% at λ=280 nm; ¹H NMR (DMSO-D₆) δ(ppm): 11.59 (br s, 1H), 7.74 (br s, 1H), 7.56 (s, 1H), 4.62 (m, 1H),3.12 (m, 2H), 2.49 (s, 3H), 2.18 (s, 3H), 1.09 (d, J=6.3 Hz, 3H); MS-ESIm/z 308 [M+1]⁺, 249, 206 (100%), 103. Apo6885: 95 mg, RT=8.4 min, HPLCpurity (AUC): 99% at λ=280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 11.65 (br s,1H), 7.67 (s, 1H), 7.63 (br s, 1H), 4.43 (m, 1H), 3.39 (m, 1H), 2.93 (m,1H), 2.62 (d, J=4.7 Hz, 3H), 2.18 (s, 3H), 1.07 (d, J=6.9 Hz, 3H);MS-ESI m/z 308.0 [M+1]⁺, 249, 206 (100%), 103.

Example 22 Preparation of5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one(Apo7053)

(a) To a suspension of3-hydroxy-2-methyl-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(5.33 g, 23.9 mmol) and acetonitrile (50 mL) was added potassiumcarbonate (4.96 g, 35.9 mmol). The mixture was stirred at roomtemperature and iodomethane (15 mL, 239.8 mmol) was added. The progressof the reaction was monitored by HPLC (Column: XTerra MS C18, 4.6×250mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organic phase:CH₃CN; Flow rate=1.0 mL/min; Injection volume=5 μL; Wavelength (λ): 220,254, 280, 450 nm. Gradient method; min-B % 0-5, 15-55, 25-55, 25.05-5,30-5.

After stirring at room temperature for 1 h, HPLC analysis of thereaction mixture indicated about 80% conversion. The reaction mixturewas filtered. Both the solid and the filtrate were collected. The solidwas washed with acetonitrile (40 mL×2), followed by DI water and finallywith ether to give3-hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one.Crop 1, 1.14 g, Yield=20%.

The filtrate was combined with the acetonitrile washing solutions andconcentrated to dryness to give a solid. This solid was washed with DIwater and ether to give a second crop of the desired product (2.46 g,44%). Total yield (crops 1 and 2)=64%; ¹H NMR (CD₃OD) δ (ppm): 7.79 (s,1H), 5.43 (q, J=7.2 Hz, 1H), 3.88 (s, 3H), 2.44 (s, 3H).

(b) Thionyl chloride (7.5 mL, 102.7 mmol) was added dropwise to asuspension of3-hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(3.00 g, 12.7 mmol) and acetonitrile (110 mL) with external coolingusing a tap water bath under a blanket of nitrogen. The progress of thereaction was monitored by TLC (eluant: methanol: dichloromethane, 1:10,v:v). After the addition of SOCl₂, a clear solution resulted, and whitesolid gradually formed upon further stirring. The reaction mixture wasconcentrated repeatedly in acetonitrile to give a solid, which was thencollected and washed with acetonitrile (15 mL×2). Thus,5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-onehydrochloride, was obtained as a white solid (2.89 g). Yield=78%; ¹H NMR(DMSO-D₆) δ (ppm): 8.17 (s, 1H), 6.19 (q, J=7.5 Hz, 1H), 3.84 (s, 3H),2.35 (s, 3H).(c) A mixture of5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-onehydrochloride (395 mg, 1.4 mmol) and acetonitrile (30 mL) was added to a40 wt % dimethylamine in water (3.5 mL, 27.7 mmol). The resultingyellowish solution was stirred vigorously, and the progress of thereaction was monitored by TLC (eluant: methanol/dichloromethane, 1/10,v/v). The starting material was completely consumed within 5 min. Thereaction mixture was concentrated to give a solid. The solid wasdissolved in dichloromethane (30 mL), which was then washed with a 10%ammonium chloride solution (15 mL×2). The organic phase was dried oversodium sulfate, filtered, and concentrated to give5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one(Apo7053) as a solid product (200 mg). Yield=56%; HPLC Method 1, RT=10.2min, HPLC purity (AUC): 98.3% at 280 nm); ¹H NMR (DMSO-D₆) δ (ppm): 7.68(s, 1H), 4.86 (q, J=10.1 Hz, 1H), 3.73 (s, 3H), 2.29 (s, 3H), 2.23 (s,6H). MS-ESI m/z 265 [M+1]⁺, 220 (100%), 192.

In a similar manner, the following compounds were prepared:

(i)3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one(Apo7054) was prepared from the reaction of5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-onehydrochloride (304 mg, 1.0 mmol) and piperidine (2.0 mL, 20.3 mmol). Thereaction was completed within 20 min, and Apo7054 was obtained as asolid product (232 mg). Yield=73%; HPLC Method 1, purity (AUC)=99.4% at280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 7.66 (s, 1H), 4.83-4.94 (m, 1H), 3.71(s, 3H), 2.56 (m, 2H), 2.41 (m, 2H), 2.27 (s, 3H), 1.46 (br, 4H), 1.28(br, 2H); MS-ESI m/z 305 [M+1]⁺ (100%), 220.(ii)3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(1H-imidazol-1-yl)ethyl]pyridin-4(1H)-one(Apo7055) was prepared from5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-onehydrochloride (505 mg, 1.7 mmol) and imidazole (3.5 g, 51.4 mmol). Thereaction was stopped when analysis of the HPLC chromatogram (Method 1)of the reaction mixture indicated higher than 98% conversion. Thereaction mixture was concentrated to give a solid. The solid wasdissolved in de-ionized water (4 mL), and the pH of the solution wasadjusted to 6.5 with a 6.00 N hydrochloric acid solution. The resultingsolution was repeatedly extracted with dichloromethane (15 mL×4, 30mL×2). The organic fractions were combined, dried over sodium sulfate,filtered, and concentrated. The desired compound Apo7055 was obtained asa solid from dichloromethane (320 mg). Yield=64%; HPLC purity (AUC):99.7% at 280 nm); ¹H NMR (DMSO-D₆) δ (ppm): 8.15 (s, 1H), 7.98 (s, 1H),7.52 (s, 1H), 6.96 (s, 1H), 6.66 (q, J=9.1 Hz, 1H), 3.76 (s, 3H), 2.29(s, 3H). MS-ESI m/z 288 [M+1]⁺, 220 (100%).(iii)3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(methylamino)ethyl]pyridin-4(1H)-one(Apo7056) was prepared from5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-onehydrochloride (400 mg, 1.4 mmol) and methylamine (3.0 mL, 34.4 mmol).The reaction was essentially completed within 15 min. The reactionmixture was concentrated to give a solid. A sample of salt free Apo7056product was obtained by purification using the Biotage© instrument (C18reversed phase; eluant: water and acetonitrile; gradient, 100:0 to100:4). (48 mg). HPLC Method 1, RT=8.52 min, HPLC purity (AUC): 99.3% at280 nm); ¹H NMR (CD₃OD) δ (ppm): 7.77 (s, 1H), 4.58 (q, J=8.0 Hz, 1H),3.80 (s, 3H), 2.44 (s, 3H), 2.35 (s, 3H). MS-ESI (m/z) 251.2 [M+1]⁺,220.2 (100%).(iv)3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridin-4(1H)-onehydrochloride (Apo7063) was prepared from5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-onehydrochloride (550 mg, 1.9 mmol) and 1-methylpiperazine (3.0 mL, 27.0mmol) was added. The reaction was stopped when analysis of the HPLCchromatogram (Method 1) of the reaction mixture complete conversion. Thereaction mixture was concentrated to give a solid. To the solid wasadded methanol (2 mL), the mixture was vortexed and filtered. Thus,Apo7063 was obtained as a solid (280 mg). Yield=41%; HPLC Method 1,purity (AUC)=99.8% at 280 nm; ¹H NMR (DMSO-D₆+a few drops of D₂O) δ(ppm): 7.69 (s, 1H), 4.93 (q, J=9.7 Hz, 1H), 3.70 (s, 3H), 2.60-3.40 (b,8H), 2.69 (s, 3H), 2.29 (s, 3H); MS-ESI m/z 320 [M+1]⁺ (100%), 220.

Example 23 Preparation of2-(dimethylamino)-3-hydroxy-1-methyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one(Apo7077)

Thionyl chloride (1.6 mL, 21.9 mmol) was added dropwise to a suspensionof5-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(0.82 g, 3.7 mmol) and acetonitrile (30 mL) under a blanket of nitrogen.The reaction was heated to reflux and a clear solution resulted. Theprogress of the reaction was monitored by TLC (eluant: methanol:dichloromethane, 1:10, v: v). The reaction mixture was concentratedrepeatedly in acetonitrile to give a solid, which was used in the nextstep without further purification. ¹H NMR (DMSO-D₆) δ (ppm): 8.35 (s,1H), 7.62 (s, 1H), 6.77 (m, 1H), 4.12 (s, 3H).

A solution of the chloride product from the previous step inacetonitrile was added to a solution of dimethylamine (40 wt % in water,9.0 mL, 71.1 mmol). The mixture was stirred vigorously. The progress ofthe reaction was monitored by TLC (eluant: methanol/dichloromethane,1/10, v/v), and by HPLC (Method 1, RT of Apo7077=13.37 min, conversionwas about 78%). The reaction mixture was concentrated to dryness. Theresidue was taken up in dichloromethane (30 mL), then washed withde-ionized water. The organic phase was dried over sodium sulfate,filtered, and concentrated to give a crude solid. Purification of thecrude by column chromatography on silica gel (eluant:methanol/dichloromethane, 5/100, v/v) afforded Apo7077 (280 mg).Yield=30%; HPLC purity (AUC): 99.2% at 280 nm; ¹H NMR (DMSO-D₆) δ (ppm):6.23 (s, 1H), 3.93 (q, J=10.7 Hz, 2H), 3.63 (s, 3H), 2.74 (s, 6H); ¹⁹FNMR (DMSO-D₆) δ (ppm): −63.37 (t, J=50.8 Hz); MS-ESI m/z 251 [M+1]⁺(100%), 236, 221, 207, 166.

Example 24 Preparation of2-((dimethylamino)methyl)-3-hydroxy-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(Apo7081)

Thionyl chloride (0.48 mL, 6.6 mmol) was added dropwise to a suspensionof3-hydroxy-2-(hydroxymethyl)-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.50 g, 5.9 mmol) in acetonitrile (45 mL). The progress of the reactionwas monitored by TLC (eluant: methanol: dichloromethane, 15:100, v: v),and the starting material was consumed within 5 min. The reactionmixture was concentrated repeatedly in acetonitrile to give a solid,which was then washed with acetonitrile (15 mL×1). Thus,2-(chloromethyl)-3-hydroxy-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-onehydrochloride was obtained as a white solid (1.18 g).

The latter compound was dissolved in acetonitrile (20 mL) and added to asolution of dimethylamine (40 wt % in water, 15 mL, 118.5 mmol). Theresulting yellowish solution was stirred vigorously, and the progress ofthe reaction was monitored by HPLC Method: Column: XTerra MS C18,4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organicphase: CH₃CN; Flow rate=1.0 mL/min; Injection volume=5 μL; Wavelength(λ): 220, 254, 280, 450 nm. Gradient method; min-B % 0-5, 15-55, 25-55,25.05-5, 30-5. (RT of Apo7081=9.45 min, HPLC purity (AUC): about 60% atλ=280 nm). The reaction mixture was concentrated to give a solid. To thesolid was added de-ionized water (15 mL) and methanol (100 mL), theresulting mixture was stirred and filtered. The filtrate was collectedand concentrated in vacuo. The residue was purified by columnchromatography on silica gel (eluant: methanol/dichloromethane, 5/100,v/v). Thus, Apo7081 was obtained (24 mg). HPLC Method 1, RT=9.59 min,purity (AUC): 98.6% at 280 nm; ¹H NMR (CD₃OD) δ (ppm): 6.82 (s, 1H),5.54 (q, J=6.2 Hz, 1H), 3.96 (s, 3H), 3.76 (s, 2H), 2.32 (s, 6H); MS-ESIm/z 281 [M+1]⁺, 236 (100%), 208.

Example 25 Preparation of5-hydroxy-1-methyl-2-(2,2,2-trifluoro-1,1-dihydroxyethyl)pyridin-4(1H)-one(Apo7072)

(a) To an ice-salt cooled suspension of5-(benzyloxy)-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one(1.20 g, 3.8 mmol) and a 10% sodium bicarbonate solution (4 mL) inacetone (36 mL) were placed in a 250-mL 1-N RB equipped with a magneticstir bar to give a suspension was added a solution of potassium bromate(99 mg, 0.6 mmol) dissolved in de-ionized water (3 mL). A solution ofTEMPO (31 mg, 0.2 mmol) in acetone (1 mL) was added to the suspension,followed by a solution of sodium hypochlorite (0.96 M, 6.5 mL, 6.24mmol). HPLC was used to monitor the progress of the reaction (HPLCColumn: XTerra MS C18, 4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mMEDTA, pH 7.4; B=Organic phase: CH₃CN; Flow rate=1.0 mL/min; Injectionvolume=5 μL; Wavelength (λ): 220, 254, 280, 450 nm. Isocratic method;aqueous: organic=75:25, RT of the SM=10.30 min, RT of the product=11.37min, the conversion was >99%). The reaction mixture was filtered. Thefiltrate was collected and concentrated to give a semi-solid. Thesemi-solid was suspended in dichloromethane (40 mL) and brine (30 mL).The mixture was stirred and the solid was collected by suctionfiltration. The solid was washed with de-ionized water (15 mL×4) andwith ether (15 mL×4). Thus,5-(benzyloxy)-1-methyl-2-(2,2,2-trifluoro-1,1-dihydroxyethyl)pyridin-4(1H)-onewas obtained (0.93 g). Yield=73%; HPLC Method 2, purity (AUC)=99.4% at280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 8.45 (s, 2H), 7.67 (s, 1H), 7.4 (m,5H), 6.66 (s, 1H), 5.04 (s, 2H), 3.85 (s, 3H); MS-ESI m/z 330 [M+1]⁺, 91(100%).(b) Debenzylation of5-(benzyloxy)-1-methyl-2-(2,2,2-trifluoro-1,1-dihydroxyethyl)pyridin-4(1H)-one(700 mg, 2.1 mmol) was carried out in a hydrochloric acid solution (4M,22 mL) by heating to reflux. HPLC was used to monitor the progress ofthe reaction (HPLC Method 2, RT of the SM=11.47 min, RT of theproduct=3.26 min, conversion >98%). The resulting solution wasconcentrated to give oil. About half of the oily residue was weighedout, and dissolved in de-ionized water. The pH of the resulting solutionwas adjusted to 6 with a 6.00 N sodium hydroxide solution (160 μL).Solid appeared upon stirring. The solid was collected by filtration,thoroughly washed with de-ionized water and ether. Thus, a sample of5-hydroxy-1-methyl-2-(2,2,2-trifluoro-,1-dihydroxyethyl)pyridin-4(1H)-one (Apo7072) was obtained (118 mg).Yield=46%; HPLC Method: Column: XTerra MS C18, 4.6×250 mm; A=Aqueousphase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organic phase: CH₃CN; Flowrate=1.0 mL/min; Injection volume=5 μL; Wavelength (λ): 220, 254, 280,450 nm. Isocratic method; aqueous: organic=75:25, purity (AUC)=99.5% at280 nm; ¹H NMR (DMSO-D₆+a few drops of D₂O) δ (ppm): 7.47 (s, 1H), 6.66(s, 1H), 3.82 (s, 3H); MS-ESI m/z 240 [M+1]⁺, 222 (100%), 125.

Example 26 A. pKa Determination by Potentiometric Titration

The pKa values of ligands were determined by potentiometric titrationwhen a ligand concentration >1×10⁻² M in water could be prepared. In atypical experiment, the sample solution (1.00×10⁻² M) was prepared bythe following method: Apo7041 (125.4 mg) was weighed into a 50 mLvolumetric flask, and about 40 mL of 0.1 M NaCl was added. The mixturewas sonicated for 10 min to give a clear colorless solution. More of the0.1 M NaCl was added to volume and the resulting solution was vortexedto mix. 40 mL of the solution was transferred into a T70 titration cellby using a 10 mL digital pipet. A 6.000 N sodium hydroxide solution (127μL, 1.9 equiv) was added, and the pH (11.82) of the solution wasrecorded. The solution was allowed to equilibrate at 22° C. for 5 min.

The solution was then titrated against a 6.000 N hydrochloric acidsolution at 22° C. by using a Mettler Toledo T70 autotitrator, until thepH reached 1.5. The volume of acid added and the pH reading wererecorded. Thus, 501 measurements were taken for this experiment.

The data set of pH vs. acid volume was analyzed using Hyperquad 2000software (version 2.1, Peter Gans, University of Leeds). The pKa valueswere obtained using the model: L⁻+H⁺⇄LH (pKa₁), LH+H⁺⇄LH₂ ⁺, and LH₂⁺⇄H⁺⇄LH₃ ²⁺ (pKa₃). Thus, Apo7041 has pKa₁=9.39, pKa₂=3.52, andpKa₃=1.66 as determined potentiometrically.

B. pKa Determination by Spectrophotometric Titration

The pKa values of ligands can be determined by spectrophotometrictitration when both the conjugated acid and base absorb in theUV-visible region. In a typical experiment, the sample solution wasprepared by the following method: Apo7041 stock solution (12.74 mg) wasweighed into a 10 mL volumetric flask, and 0.1 M NaCl solution was addedto volume. The mixture was sonicated and voltexed to give a clearcolorless solution. The concentration of Apo7041 of this stock solutionis 5.1×10⁻³ M.

Apo7041 sample solution: 727 μL of the above stock solution wastransferred into a 50 mL volumetric flask by using a 1000 μL digitalpipet, and 0.1 M NaCl was added to volume. The resulting solution wasvortexed to mix to give a sample solution. The concentration of Apo7041of this sample solution is 7.4×10⁻⁵ M. 20 mL of the sample solution wastransferred into a 35 mL beaker by using a 10 mL digital pipet. Thesample solution was circulated between the beaker and the flow cellusing a sipper system.

The sample solution was titrated against standard hydrochloric acidsolutions at 22° C. to reach pH 1.11. After each addition of acid thesolution was allowed to equilibrate until a constant pH reading wasreached. The pH and the UV-Vis spectrum were recorded for eachmeasurement. The solution was titrated until there was no obvious changein the spectra after several subsequent additions of acid. Thus, 30measurements were recorded.

The resulting data set was then analyzed using pHAB (Peter Gans,University of Leeds). The pKa values were obtained using the model:LH+H⁺⇄LH₂ ⁺, and LH₂ ⁺+H⁺⇄LH₃ ²⁺ (pKa₃). Thus, Apo7041 has pKa_(2=3.51),and pKa_(3=1.23) as determined spectrophotometrically.

Example 27 Stoichiometry of Fe-Complexes by Job's Method

In a typical experiment Fe-Apo7053 complex solutions were prepared bymixing a stock solution of Fe²⁺ (atomic absorption standard, 989 μg/mLin 1 wt % HCl, Aldrich) and a stock solution of Apo7053 (7.88×10⁻³ M in0.1 M MOPS, pH 7.4). Twelve sample solutions were prepared. While thesum of the total iron concentration ([iron]_(total)) and the totalligand concentration ([L]_(total)) in each of the 12 sample solutionswere kept constant (8.00×10⁻⁴ M), the molar fraction of the ligand, α(α=[L]_(total)/([L]_(total)+[iron]_(total))), for the 12 samplesolutions were different, and were prepared as 0.0, 0.1, 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.75, 0.8, 0.9 and 1.0, respectively. The total volumefor each of the 12 sample solutions was 5 mL, using MOPS (0.1 M, pH 7.4)as the solvent. The pH of the 12 solutions were adjusted to pH 7.4 withNaOH. The sample solutions were vortexed at rt for 2.5 h, and thenstayed at rt overnight. The sample solutions were centrifuged at 4000rpm for 15 min. The UV-Vis spectrum was recorded at 22° C. for each ofthe 12 solutions.

A Job's plot was created with the absorbance at 458 nm as the y-axis andα as the x-axis. A maximum absorbance was found at α=0.75, whichcorresponds to an iron:ligand ratio of 1:3 in the complexes. The Job'splot result is shown in FIG. 3A.

Proceeding in a similar manner, the Job's plot for Fe-Apo7041 wascreated, and is shown in FIG. 3B.

Example 28 Distribution Coefficient Determination, D_(7.4)

K₂HPO₄ buffer (50 mM, pH=7.4) and 1-octanol were used as the aqueousphase and the organic phase, respectively. The K₂HPO₄ buffer and1-octanol were mixed, and pre-saturated with each other before use.

In a typical experiment, an aqueous solution of Apo6995(3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one) wasprepared by weighing out 3 mg of the compound into a 10-mL test-tube. Itwas then mixed with K₂HPO₄ buffer (2 mL) and sonicated for 30 minuteswith frequent vortexing. The solution was then filtered through HPLCsyringe filter (4 mm PVDF syringe filter 0.45 μM) to obtain the aqueoussolution. It was analyzed by HPLC (Column: Waters Symmetry C₁₈, 5 μM,3.9×50 mm; Mobile phase: 0.035% HClO₄/ACN; Gradient method: time inminutes—ACN in %: 0-10, 10-90, 12-90, 14-10, 16-10; Flow rate: 1 mL/min;Injection volume=2 μL; detector wavelength: 270 nm) to obtain the peakheight (H_(I)).

One mL of this aqueous solution was pipetted out into another 10-mLtest-tube and mixed with 1 mL of 1-octanol. The mixture was thenvortexed for 1 hour. The solution was centrifuged at 2000 rpm for 10minutes. A small amount of the lower aqueous layer was carefullypipetted out and analyzed by HPLC to obtain the peak height (H_(F)). Thedistribution coefficient, D_(7.4), was calculated using the followingequation: D_(7.4)=(H_(I)−H_(F))/H_(F).

In a similar fashion, D_(7.4) was determined for the followingcompounds:

Apo# D_(7.4) Log D_(7.4) Deferiprone 0.17 −0.77 6995 2.51 0.40 7030 5.930.77 7040 8.76 0.94 7060 4.93 0.69 7065 4.93 0.69 7066 4.69 0.67 70672.82 0.45 7069 0.66 −0.18 7070 1.72 0.23 7083 1.70 0.23

Example 29 Determination of Metal Complexation Constants A. Instrumentaland Chemicals:

For spectrophotometric titration, a pH meter (Accumet Research AR15,13-636-AR15, Fisher) and a combination electrode (Accumet Standard-sizeGlass Combination Electrode, 13-620-285, Fisher) were used for pHmeasurements. Before using, the electrode was calibrated with threestandard buffer solutions (pH 4.00, pH 7.00, and pH 10.00, Fisher). Thetitrant was added manually by using digital pipettes (Eppendorf). AnUV-visible spectrophotometer (Agilent 8453) was used for UV-Visabsorbance measurements.

A sipper system (89068D Agilent) was used whenever pH-dependentabsorbencies were measured. A vortexer (VX-2500 Multi-tube Vortexer, VWRScientific Products) was used for the preparation of sample solutions inboth distribution coefficient and Job's plot experiments.

For potentiometric titration, an autotitrator (Mettler Toledo T70) and acombination electrode (Mettler Toledo DG 115-SC) were used. Beforeusing, the electrode was calibrated with three standard buffer solutions(pH 4.00, pH 7.00, and pH 10.00, Fisher). The titrant was addedautomatically by using T70. The data set of pH vs. titrant volume wasrecorded.

The metal stock solutions were purchased from Aldrich: Iron atomicabsorption standard solution (1000 μg/ml of Fe in 1 wt. % HCl); Aluminumatomic absorption standard solution (1000 μg/ml of Al in 1 wt % HCl);Calcium atomic absorption standard solution (1000 μg/ml of Ca in 1 wt. %HCl); Copper atomic absorption standard solution (1000 μg/ml of Cu in 1wt. % HNO₃); Magnesium atomic absorption standard solution (1000 μg/mlof Mg in 1 wt. % HNO₃); Manganese atomic absorption standard solution(1000 μg/ml of Mn in 1 wt. % HNO₃); Zinc atomic absorption standardsolution (1000 μg/ml of Zn in 1 wt. % HCl). The standard SodiumHydroxide and Hydrochloric acid solutions were purchased from VWRScientific Products. MOPS (3-[N-Morpholino]propanesulfonic acid) waspurchased from Sigma-Aldrich.

B. Determination of Stepwise Formation Constants for Fe-Apo7041 Systemby Spectrophotometric Titration in 0.1M NaCl Solution

Stepwise formation constants for M^(n+)-ligand systems were determinedby spectrophotometric titration when metal complexes have a strongabsorbance in the visible region due to ligand to metal charge transfer.

In a typical experiment, the sample solution was prepared according tothe following procedure: compound Apo7041 (12.96 mg) was weighed into a50 mL volumetric flask, and about 40 mL of 0.1 M NaCl was added. Themixture was sonicated for 10 min to give a clear colorless solution. Theiron stock solution (atomic absorption standard, Aldrich, 565 μL, 10.00μmol) was pipetted into the solution, followed by the addition of 1.000N NaOH (170 μL). More of the 0.1 M NaCl was added to volume and theresulting solution was vortexed to mix. The molar ratio between thetotal iron and the total Apo7041 was 1/5.1. The mixture was vortexed atrt for 1 h. 20 mL of the sample solution was transferred into a 35 mLbeaker by using a 10 mL digital pipet. The sample solution wascirculated between the beaker and the flow cell using a sipper system.The sample solution was titrated against hydrochloric acid solutions at22° C. until the pH reached 0.021. After each addition of acid, thesolution was allowed to equilibrate until a constant pH reading wasreached. The pH and the UV-Vis spectrum were recorded for eachmeasurement. For each measurement enough acid was added so that therewas a slight decrease in the absorbance of the spectrum. Altogether, 68measurements were taken to finish the experiment.

The resulting data set was then analyzed using pHAB. The formationconstants for Fe-Apo7041 system were optimized using the model shown inthe first column of the table. The results are shown in the Table 29Bbelow.

TABLE 29B The model symbol value Fe³⁺ + LH ⇄ (FeLH)³⁺ Log β₁₁₁ 18.1(FeLH)³⁺ + LH ⇄ (FeL₂H₂)³⁺ Log β₁₂₂ 35.0 (FeL₃H₂)²⁺ + H⁺ ⇄ (FeL₃H₃)³⁺Log β₁₃₃ 50.5 (FeL₃H)⁺ + H⁺ ⇄ (FeL₃H₂)²⁺ Log β₁₃₂ 48.3 (FeL₃)⁰ + H⁺ ⇄(FeL₃H)⁺ Log β₁₃₁ 44.5 Fe³⁺ + 3L⁻ ⇄ (FeL₃)⁰ Log β₁₃₀ 38.8 L⁻ + H⁺ ⇄ LHpKa₁ 9.39 LH + H⁺ ⇄ LH₂ ⁺ pKa₁ + pKa₂ 12.91 LH₂ ⁺ + H⁺ ⇄ LH₃ ²⁺ pKa₁ +pKa₂ + pKa₃ 14.57

C. Determination of Stepwise Formation Constants for Cu-Apo7041 Systemby Potentiometric Titration in 0.1M Aqueous NaCl/MeOH, 1/1, v/v Mixture

Stepwise formation constants for Cu²⁺-ligand system were determined bypotentiometric titration when metal complexes (≧0.002 M) do notprecipitate during titration. In a typical experiment, the samplesolution was prepared by the following method: Apo7041 (126.1 mg, 0.50mmol) was weighed into a 50 mL volumetric flask, and about 35 mL of amixed solvent (0.1 M NaCl aqueous:MeOH, 1:1, v:v) was added. The mixturewas sonicated for 10 min to give a clear colorless solution. The copperstock solution (atomic absorption standard, Aldrich, 6.33 mL, 0.10 mmol)was pipetted into the solution. More of the mixed solvent was added tovolume and the resulting solution was vortexed to mix. The molar ratiobetween the total copper and the total Apo7041 was 1/5. 40 mL of thesolution was transferred into a T70 titration cell by using a 10 mLdigital pipet. A 6.000 N sodium hydroxide solution (300 μL) was added,and the pH (12.17) of the solution was recorded. The solution wasallowed to equilibrate at 22° C. for 5 min.

The solution was then titrated against a 6.000 N hydrochloric acidsolution at 22° C. by using a Mettler Toledo T70 autotitrator, until thepH reached 1.5. The volume of acid added and the pH reading wererecorded. Thus, 533 measurements were taken for this experiment.

The pKa values of Apo7041 in the same mixed solvent were also determinedby potentiometric titration using the procedure described in Example 1.

The data set of pH vs. acid volume for Cu-Apo7041 system was analyzedusing Hyperquad 2000 software (version 2.1, Peter Gans, University ofLeeds). The formation constants for Cu-Apo7041 system were optimizedusing the model shown in the first column of Table 29C. The results areshown in the second and third column.

TABLE 29C The model symbol value (CuL₂H)⁺ + H⁺ ⇄ (CuL₂H₂)²⁺ Log β₁₂₂27.9 (CuL₂)⁰ + H⁺ ⇄ (CuL₂H)⁺ Log β₁₂₁ 23.0 Cu²⁺ + 2L⁻ ⇄ (CuL₂)⁰ Log β₁₂₀17.3 L⁻ + H⁺ ⇄ LH pKa₁ 10.1 LH + H⁺ ⇄ LH₂ ⁺ pKa₁ + pKa₂ 13.3 LH₂ ⁺ + H⁺⇄ LH₃ ²⁺ pKa₁ + pKa₂ + pKa₃ 15.3

D. Determination of Stepwise Formation Constants for Zn-Apo7041 Systemby Potentiometric Titration in 0.1M Aqueous NaCl/MeOH, 1/1, v/v Mixture

Stepwise formation constants for Zn²⁺-ligand system were determined bypotentiometric titration when metal complexes (≧0.002 M) do notprecipitate during titration. In a typical experiment, the samplesolution was prepared by the following method: Apo7041 (126.3 mg, 0.50mmol) was weighed into a 50 mL volumetric flask, and about 35 mL of amixed solvent (0.1 M NaCl aqueous: MeOH, 1:1, v:v) was added. Themixture was sonicated for 10 min to give a clear colorless solution. Thezinc stock solution (atomic absorption standard, Aldrich, 6.64 mL, 0.10mmol) was pipetted into the solution followed by addition of sodiumhydroxide solution (6.000 N, 300 μL). More of the mixed solvent wasadded to volume and the resulting solution was vortexed to mix. Themolar ratio between the total zinc and the total Apo7041 was 1/5. 40 mLof the solution was transferred into a T70 titration cell by using a 10mL digital pipet. A 6.000 N sodium hydroxide solution (160 μL) wasadded, and the pH (11.95) of the solution was recorded. The solution wasallowed to equilibrate at 22° C. for 5 min.

The solution was then titrated against a 6.000 N hydrochloric acidsolution at 22° C. by using a Mettler Toledo T70 autotitrator, until thepH reached 1.5. The volume of acid added and the pH reading wererecorded. Thus, 523 measurements were taken for this experiment.

The data set of pH vs. acid volume for Zn-Apo7041 system was analyzedusing Hyperquad 2000 software (version 2.1, Peter Gans, University ofLeeds). The formation constants for Zn-Apo7041 system were optimizedusing the model shown in the first column of the table 29D. The resultsare shown in the second and third column.

TABLE 29D The model symbol value Zn²⁺ + LH ⇄ (ZnLH)²⁺ Log β₁₁₁ 13.1(ZnL₂)⁰ + H⁺ ⇄ (ZnL₂H)⁺ Log β₁₂₁ 19.6 Zn²⁺ + 2L⁻ ⇄ (ZnL₂)⁰ Log β₁₂₀ 13.2L⁻ + H⁺ ⇄ LH pKa₁ 10.1 LH + H⁺ ⇄ LH₂ ⁺ pKa₁ + pKa₂ 13.3 LH₂ ⁺ + H⁺ ⇄ LH₃²⁺ pKa₁ + pKa₂ + pKa₃ 15.3Calculation of pM^(n+)

pM^(n+) is defined as −log [M(H₂O)_(m)]^(n+) at physiologicalconditions, i.e.: pH 7.4, a ligand concentration of 10 μM, and a metalconcentration of 1 μM. To calculate pM^(n+) for a ML_(n) system, β_(n)and pKa values are needed (β_(n) are the formation constants forM^(n+)+n L⁻⇄ML_(n); pKa are the equilibrium constants for L⁻+n H⁺⇄LH_(n)^((n-1)+)). The pM^(n+) is calculated using the Hyss software (HYSS©2000 Protonic Software).

The data obtained from the above determinations for Apo7041, a compoundof formula I, can be found in Table 1.

Example 30 Cyclic Voltammetry

A criterion in the design of compounds of formula I concerns controllingthe redox potential of the Fe-chelate system at pH 7.4 to a negativevalue below −320 my (vs NHE) to prevent any reactions with oxygenspecies. Iron exists in multiple states including Fe²⁺ and Fe³⁺. Theiron (II)/iron (III) pair can act as a pair of one electron reducingagent and oxidizing agent. According to Crumbliss(http://www.medicine.uiowa.edu/FRRB/VirtualSchool/Crumbliss-Fe.pdf) andPierre (BioMetals, 12, 195-199, 1999), selective chelation of iron withredox potential control is a means to prevent iron from participating ina catalytic cycle to produce toxic hydroxyl radicals and/or reactiveoxygen species (ROS) (e.g. via the Fenton reaction or Haber Weisscycle). The Fe (III)-tris-chelate system with redox potential below −320my (vs NHE or −540 my vs Ag/AgCl) at pH 7.4 will not be reduced by anybiological reducing agents such as NADPH/NADH, therefore it will notparticipate in the Haber Weiss cycle to generate ROS (reactive oxygenspecies). Within the mammalian body, iron is bound to different proteinssuch as transferrin in human blood to ensure it remains in a form thatcannot react with any oxygen molecules. The E_(1/2) value ofFe-transferrin is −500 my (vs. NHE or −720 my vs. Ag/AgCl).

The redox potential of iron complexes can be measured by cyclicvoltammetry (CV). The use of CV to measure the redox potentials of ironchelates deferiprone, deferrioxamine and Apo7041 (a representativecompound of this invention) as chelators respectively, is illustrated inFIG. 1. Iron chelates such as Fe-desferrioxamine (DFO) andFe-(deferiprone)₃ have redox potential E_(1/2) values at −480 my (vs.NHE) and −628 my (vs. NHE), respectively, at pH 7.4. Compounds offormula I such Fe(Apo7041)₃ has a E_(1/2) value of −530 my (vs. NHE)slightly more negative when compared to that of desferrioxamine. Thecyclic voltammogram of Fe-DFO, Fe(deferiprone)₃ and Fe(Apo7041)₃ can befound in FIG. 1. One advantage of the chelators of this invention isthat the redox potentials of their iron chelates lie in the extremenegative range at physiological pH 7.4, therefore their iron chelateswill not participate in the redox cycle to generate reactive oxygenspecies at physiological pH. When combined with other novel propertiesas described in this invention, the compounds of formula I are effectiveagents in the removal of iron via a chelation mechanism.

Determination of E_(1/2) of Fe(Apo7041)₃

A. Materials and Instruments

Potassium ferricyanide (III) was purchased from Aldrich. Deferoxaminemesylate (DFO) was purchased from Sigma. Iron atomic absorption standardsolution (contains 1000 μg/mL of Fe in 1 wt. % HCl) was purchased fromAldrich. Electrochemical measurements were performed with a cyclicvoltammetric analyzer (BAS, CV-50W Potentiostat). Software BAS CV-50WVersion 2.31 was used. The following electrodes were used fordetermining redox potentials of the iron complexes: Ag/AgCl referenceelectrode (BAS, MF-2052); platinum auxiliary electrode (BAS, MW-1032);and glassy carbon working electrode (BAS, MF-2012). A pH meter (AccumetResearch AR15, 13-636-AR15, Fisher Scientific) and pH electrode(AccupHast combination electrode, 13-620-297, Fisher Scientific) wereused for pH adjustment of the sample solutions.

B. Preparation of Sample Solutions

2.0 mM solution of Fe(DFO) in 0.1 M NaCl (pH 7.4) 148.1 mg ofdeferoxamine mesylate (purity=95%) was accurately weighed out into a100-mL volumetric flask. The solid was dissolved in about 30 mL of 0.1 MNaCl to give a clear colorless solution. To the solution was added11.114 mL of the standard iron solution. The solution was diluted with0.1 M NaCl to the 100 ml mark in the volumetric flask. The resultingsolution was vortexed to ensure complete mixing. The solution wastransferred to a 200-mL beaker. The pH of the solution was then adjustedto about 7.1 by adding standard solutions of sodium hydroxide. Thebeaker was then covered with parafilm and the solution was left stirringfor overnight. The pH of the solution was adjusted to 7.40 in thefollowing test day. The calculated molar ratio between iron_(total) andDFO_(total) was 1:1.07.

1.0 mM solution of Fe(Apo7041)₃ in 0.1 M NaCl (pH 7.4) Apo7041 (19.8 mg,0.079 mmol) was accurately weighed out into a 25-mL round bottom flask.The solid was dissolved in about 14 mL of 0.1 M NaCl to give a clearcolorless solution. To the solution was added a standard iron solution(847 μL, 0.015 mmol) followed by addition of sodium hydroxide solution(6.000 N, 44 μL). The resulting solution was vortexed to ensure completemixing. The pH of the solution was recorded (7.5). The calculated molarratio between iron_(total) and Apo7041_(total) was 1/5.3. In a similarmanner, a solution of 2.0 mM of Fe(deferiprone)₃ in 0.1 M NaCl (pH 7.4)was prepared.

C. Determination of Redox Potentials of Iron Complexes

All potentials in the text are given versus the Ag/AgCl referenceelectrode. The redox potentials of 2.0 mM of K₃Fe(CN)₆ in 1.0 Mpotassium nitrate were measured at the beginning of each working day toverify the proper functioning of the cyclic voltammeter. The redox peakpotentials of solutions of iron complexes at pH 7.4, that is, Fe(DFO),Fe(deferiprone)₃, and Fe(Apo7041)₃, were determined. For example, theFe(Apo7041)₃ sample solution was purged with argon for approximately 15min. A solvent trap containing 0.1 M NaCl was used to reduceevaporation. Cyclic voltammograms of the sample solution were recordedusing glassy carbon electrode (working electrode), Ag/AgCl electrode(reference electrode), and platinum electrode (auxiliary electrode). Thefollowing instrument parameters were used: Init E (mV)=0; High E (mV)=0;Low E (mV)=−1200; Init P/N=N; V (mV/s)=200; No. of Sweep Segments=3;Sensitivity (μA/V)=100; Stir Speed=50 rpm.

FIG. 1 shows the cyclic voltammograms of iron(III)L_(n) complexes at pH7.4: a) Fe(Apo7053)₃; b) Fe(Apo7041)₃; c) Fe(Apo7069)₃. The reductionpeak potential (E_(p) ^(red)), the oxidation peak potential (E_(p)^(ox)), the absolute difference (ΔE_(p)) between E_(p) ^(red) and E_(p)^(ox), and redox potential (E_(1/2)) of the four iron complexes weremeasured. E_(1/2) value is calculated as (E_(p) ^(red)+E_(p) ^(ox))/2.

The cyclic voltammograms of a) Fe(Apo7053)₃; b) Fe(Apo7041)₃; c)Fe(Apo7069)₃ represent a reversible single electron transfer process foreach complex: Fe(III)L_(n)/Fe(II)L_(n). The E_(1/2) value of thereference Fe(DFO) determined in this lab is −698 mV versus the Ag/AgClreference electrode, which is in excellent agreement to literature value(−688 mV) (A. L. Crumbliss et al., Inorganic Chemistry, 2003, 42,42-50). The E_(1/2) value of Fe(Apo7041)₃ is −731 mV, which is slightlymore electronegative than that of Fe(DFO).

The Electrochemical properties of iron(III)L_(n) complexes in 0.1Maqueous NaCl at pH 7.4 are listed below. Fe(DFO), {DFO=deferioxamine B};Fe(L1)₃, {L1=deferiprone}; K₃Fe(CN)₆ are used as controls for thevalidation of the study.

E_(red) E_(ox) ΔE E_(1/2) (mV) E_(1/2) (mV) complex (mV) (mV) (mV) vs.Ag/AgCl vs. NHE K₃Fe(CN)₆ 197 282 85 +20 +240 FeDFO −754 −642 112 −698−478 Fe(L1)₃ −841 −752 89 −797 −577 Fe(7041)₃ −789 −672 117 −731 −511Fe(7053)₃ −856 −761 95 −809 −589 Fe(7069)₃ −793 −706 87 −750 −530

Example 31 Benzoic Acid Hydroxylation Assay

Benzoic acid is a hydroxyl radical scavenger and reacts with hydroxylradical to give 2-hydroxy, 3-hydroxy and 4-hydroxybenzoic acids. Thebenzoic acid hydroxylation assay is a chemical assay designed to detectdamage caused by hydroxyl radical (Dean and Nicholson, Free RadicalResearch 1994, vol 20, 83-101). For example, deferiprone suppresses theformation of hydroxybenzoic acids in the presence of iron salts andhydrogen peroxide, while EDTA and iron salts allow such hydroxylationreactions to take place.

This screening assay involves the use of iron salt, benzoic acid,hydrogen peroxide and the chelator and measures the ability of thechelator to inhibit the formation of hydroxybenzoate as an indicator toprevent hydroxyl radical formation in living system.

Compound of formula I has similar properties to deferiprone andsuppresses the formation of the hydroxybenzoic acid when benzoic acid istreated with hydrogen peroxide and iron salts. The results are shown inFIG. 9. Compounds of formula I show inhibitory effect to the hydroxylradical transformation of benzoic acid. Thus, these compounds areprotective towards hydroxyl radical oxidation in biological systems.

Briefly, this procedure is based on the ability of hydroxyl radicals tohydroxylate benzoate to give 2-, 3- and 4-hydroxylated benzoic acidproducts. Benzoic acid (1 mM) is incubated over time up to 81 h at roomtemperature in the dark in 10 mM phosphate buffer (pH 7.4) with 6 mMhydrogen peroxide, ferric chloride (30 μM) and the Fe chelator (30 μM).HPLC is the method of choice used to monitor and quantify the amount of2-, 3- and 4-hydroxylated products formed over time in the reactionmixture, and can be verified against authentic benzoic acid and itshydroxylated products via their respective retention times and areasunder curve. In addition, several controls are used: (i) a controlwithout added Fe stock solution and Fe chelator; (ii) a control withoutadded Fe chelator; (iii) EDTA as positive control; and (iv) deferiproneas negative control. The Fe-EDTA system is a hydroxyl radical generatorand is known to promote hydroxylation of benzoic acid. Under theexperimental conditions, the Fe chelate from the compounds of formula I(Apo7041, Apo7050, Apo7053 and Apo7077) do not promote the hydroxylationof benzoic acid.

Example 32 A. Neuroprotective Effect of Compounds of Formula I onHydrogen Peroxide Induced Apoptosis in SH-SY5Y Neuroblastoma Cells

Hydrogen peroxide (H₂O₂) is a major ROS (reactive oxidative stress) andcan induce apoptosis in many different cell types. One of the CNS drugdesign strategies is to use compounds with antioxidant properties as apossible treatment of both acute and chronic neurodegenerative diseases(Kang et al. Bioorganic & Medicinal Chemistry Letters, 2004, 14,2261-2264). This involves testing the compounds of this invention forits protective effect against oxidative stress-induced cell death inSH-SY5Y human neuroblastoma cells. SH-SY5Y human neuroblastoma cellswere cultured in DMEM (ATCC)/F12 (Cellgro) with 10% FBS. The cells wereplated at 30,000 cells/cm² and grown for 1 day in the regular culturemedia prior to compound addition. Cells were routinely treated with thetest compound, at a pre-determined range of concentrations, in thepresence or absence of 50 μM hydrogen peroxide in a basal mediumcontaining no FBS for 16-22 h. Cell viability was then measured usingthe routine MTT method (Mosmann, T., Rapid Colorimetric Assay forCellular Growth and Survival: Application to Proliferation andCytotoxicity Assays”. J. Immunol. Meth. 1983, 65, 55-63).

For data analysis, cell viability relative to control not treated witheither H₂O₂ or the test compound, was plotted against the compoundconcentration. The threshold protective concentration (TH) was definedas the highest concentration at which the compound did not display asignificant protective effect (i.e. next higher concentration had astatistically significant protective effect) against hydrogen peroxideinsult. Maximum effective concentration (EC₁₀₀) was a concentration atwhich the compound exhibited maximum protective effect. Cytotoxicity ofthe test compound was assessed in the absence of hydrogen peroxide.Cytotoxic concentration (CC1) was defined as the lowest compoundconcentration resulting in viability significantly below 80%. Cytotoxicconcentration (CC2) was the lowest compound concentration resulting inviability significantly below 80% in H₂O₂-treated cells.

B. Evaluation of the Compounds in the Protection Against EndogenouslyProduced Aβ Toxicity

Amyloid plaques, are formed by the aggregation of small peptides, calledamyloid β peptide (Aβ), that are produced when amyloid precursor protein(APP) is cleaved by the action of two enzymes, β-APP cleaving enzyme andγ-secretase. One approach to the treatment of Alzheimer is, therefore,limiting the production of Aβ from its precursor by inhibiting one orboth of these enzymes, while another approach is to inhibit theaggregation of Aβ via the use of metal chelators.

In this assay, human neuroblastoma cells (MC-65 cells) are geneticallyengineered to conditionally express amyloid β peptide (Aβ). The Aβproduction is suppressed by tetracycline (TET+) presence in culturemedium, and its production is activated when TET is withdrawn (TET−).The activation of Aβ production results in cell death “MC-65 suicide”.

Protective effect of compounds against edogenously produced amyloid beta(Aβ) was assessed in human neuroblastoma MC-65 cells. MC-65 cells havebeen stably transformed to conditionally express high levels of apartial amyloid precursor (AP) fusion protein (Bryce Sopher et al.,Brain Res Mol Brain Res. 1994, 207-17.). This protein is furtherproteolitically processed in the cells to form a set of AP-derived Aβpeptides. AP conditional expression in these cells is under control oftetracycline-responsive promoter system and results in pronouncedcytotoxicity. Activity of the promoter is tightly regulated by thepresence of the antibiotic tetracycline (TET) in the culture medium. Inthe presence of TET, the promoter is in the basal state and no amyloidbeta peptide is synthesized. In the absence of TET the promoter is ininduced state, resulting in the accumulation of Aβ peptides in thecells, degenerative changes in cell morphology and decreased survival.

Transfected human neuroblastoma cells (MC-65) were cultured in DMEM(ATCC) supplemented with non-essential amino acids and 10% FBS (VWR) inthe presence of TET (1 μg/mL). For the experiment, the cells were platedat 35,000 cells/cm² and grown for 1 day in the regular culture mediaprior to compound addition. On the day of assay, culture supernatant wasremoved from the wells and cells were thoroughly washed once with thecompound incubation matrix containing no FBS and no TET. MC-65 cellswere treated with a test compound at pre-determined range ofconcentrations in a basal medium containing no FBS and in the absence orpresence of 1 μg/mL TET for approximately 48 h. Cell viability was thenmeasured using the MTT method.

For data analysis, cell viabilities relative to the control not treatedwith a test compound and maintained in the presence of TET were plottedagainst the compound concentration. The threshold protectiveconcentration (TH) was defined as the highest concentration at which thetested compound did not display a significant protective effect (i.e.next higher concentration had a statistically significant protectiveeffect) in the group maintained in the absence of TET. Maximum effectiveconcentration (EC₁₀₀) was a concentration at which the compoundexhibited maximum protective effect. Cytotoxicity of the test compoundwas assessed in the cells mainteined in the presence of TET. Cytotoxicconcentration (CC1) was defined as the lowest compound concentrationresulting in viability significantly below 80%. CC2 is the lowestcompound concentration resulting in viability significantly below 80% incells expressing AP (i.e. cultured without tetracycline).

Chemical Structures of Compounds

Apo# G¹ G² G³ G⁴ 6994 H CH₂CF₃ Me H 6995 Me CH₂CF₃ H H 6998CH(CF₃)-D-ala- Me H H NHMe 7021 CH₂CF₃ Me CH₂NMe₂ H 7022 CH(OH)CF₃ MeCH₂NMe₂ H 7030 Et CH₂CF₃ H H 7032 CH(OH)CF₃ Me CH₂-L- H ala-OH 7033CH(OH)CF₃ Me CH₂-L- H ala-NHMe 7035 CH(OH)CF₃ H CH₂NMe₂ H 7038 CH(OH)CF₃Me Me Cl 7040 CH₂CF₃ Me Me Cl 7041 CH(NMe₂)CF₃ Me H H 7053 Me Me HCH(NMe₂)CF₃ 7054 Me Me H CH(piperidinyl)CF₃ 7055 Me Me HCH(imidazolyl)CF₃ 7056 Me Me H CH(NHMe)CF₃ 7057 CH(propyl- Me H Hargylamino)CF₃ 7058 CH(piperidinyl)CF₃ Me H H 7059 CH(NMe₂)CF₃ Me Me Cl7060 CH(NMe₂)CF₃ Me H Cl 7061 CH(piperidinyl)CF₃ Me H Cl 7063 Me Me HCH(N-methyl- piperazinyl)CF₃ 7065 CH₂NMe₂ CH₂CF₃ Me H 7066 CH₂CF₃ Me HCl 7067 CH₂NMe₂ Me H H 7069 Me CH₂CHF₂ H H 7071 CH₂(piperidinyl) CH₂CF₃Me H 7073 CH(N-methyl- Me H H piperazinyl)CF₃ 7074 CH (cyclo- Me H Hpropylamino)CF₃ 7075 CH (allylamino)CF₃ Me H H 7077 NMe₂ Me CH₂CF₃ H7080 CH₂CHF₂ Me H H 7083 CH2NMe₂ CH₂CHF₂ Me HTest Results of Neuroprotective effect of compounds of formula I onhydrogen peroxide induced apoptosis in SH-SY5Y neuroblastoma cells.

TH EC₁₀₀ CC1 CC2 Apo# (μM) (μM) (μM) (μM) 6994 40 160 160 640 6995 20160 320 320 6998 10 80 20 100 7021 2.5 640 80 >640 7022 5 160 40 3207030 10 320 640 >640 7032 160 640 10 >640 7035 20 640 40 >640 7038 20320 40 >640 7040 10 640 160 >640 7041 10 80 160 320 7053 10 40 2.2 >6407054 2.5 640 5 >640 7055 2.5 40 10 >640 7057 3 20 5 80 7058 5 64020 >640 7059 10 320 40 640 7060 20 320 80 >640 7061 10 640 10 10 7066 1040 160 160 7067 10 40 160 >640 7069 40 160 80 >640 7071 3 20 20 80 70735 640 40 >640 7074 3 640 20 >640 7075 3 640 20 >640 7080 10 320 40 >6407033 160 640 40 >640 7063 5 640 320 >640 7065 5 40 40 >640MC65 Assay Testing Results in the protection against endogenouslyproduced Aβ toxicity

TH EC₁₀₀ CC1 CC2 Apo# (μM) (μM) (μM) (μM) 6994 1 10 >80 >80 6995 0.1 2080 80 7021 0.1 10 10 20 7022 0.1 20 10 40 7030 1 20 40 40 7032 0.1 10 8040 7035 0.1 10 40 20 7040 1 40 40 80 7041 0.1 10 10 80 7053 0.1 10 40 207054 0.1 1 20 20 7055 1 20 40 40 7056 0.1 10 80 80 7057 1 10 20 20 70581 10 10 80 7059 1 10 10 40 7060 1 10 40 20 7061 1 10 40 20 7066 0.1 1080 80 7067 0.1 10 80 80 7069 0.1 40 80 80 7071 1 10 40 20 7073 0.1 10 4020 7074 0.1 10 10 20 7075 0.1 10 10 20 7077 1 10 80 80 7080 0.1 10 40 407083 0.1 10 40 40

Example 33 Influence of MPP⁺ (5 mM) on SV-NRA Cell Viability and theNeuroprotective Actions of Compounds of Formula I (Apo6995, Apo7060,7021) on MPP⁺ Treated SV-NRA Cells

SV-NRAs cells were plated in a 96-well plate at a density of 10,000cells/well in 100 μL of DME (dimethoxyethane), High glucose 1× liquid(Sigma) supplemented with 10% heat-inactivated FBS and 1×antibiotic/antimycotic solution (Sigma). On the next day, the cells werewashed with EMEM media (Eagle's minimal essential media; phenol red,serum and glutamine free) and treated for 24 h with 5 mM MPP⁺(1-methyl-4-phenylpyridinium) in EMEM media in the presence or absenceof a tested iron chelating compound. All compounds were tested at thefollowing concentrations: 10 μM, 20 μM, and 40 μM. After 24 h ofincubation, cell viability was determined with MTT((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellowtetrazole) assay which measures mitochondrial activity (Carmichael etal. Cancer Research 1987, 47, 936-942). MTT solution (10 μL, 5 mg/mL)was added to the wells and incubated for 2 h. Formazan product wassolubilized with 100 μL of 10% SDS (sodium dodecyl sulphate) in 0.01MHCl. Optical density was determined at 570 nm using Multiscan Ascentplate reader (Labsystems) and data collected were corrected forbackground signal measured at 650 nm. All data are expressed as % ofcontrol.

MPP+ treatment resulted in about 40%-50% decrease in cell viabilitycomparing to vehicle-treated control. Co-treatment with iron chelatorsprotected the cells from MPP⁺ toxicity. Treatment with 20 μMdeferiprone, an iron chelator drug resulted in about 20% increase incell viability (p<0.05). Treatment with iron chelators Apo7060, Apo6995and Apo7021 at concentrations of 10, 20, and 40 μM also increased cellviability by 20-30% (p<0.05) compared to MPP+ only treated cells.Representative results are shown in FIGS. 10, 11, 12, and 13.

What is claimed is:
 1. A compound of Formula I:

wherein G¹ is H, C₁-C₄ alkyl or CH₂OH; G² is (CH₂)_(n)CF₂R³, where n is1, and R³ is H or F; G³ is H or C₁-C₄ alkyl; and G⁴ is H.
 2. Thecompound of claim 1 wherein R³ is H.
 3. The compound of claim 1 whereinR³ is F.
 4. The compound of claim 3 wherein G¹ is hydrogen, and G³ ismethyl.
 5. The compound of claim 3 wherein G¹ is methyl, and G³ is H. 6.The compound of claim 3 wherein G¹ is ethyl, and G³ is H.
 7. Thecompound of claim 3 wherein G¹ is H, and G³ is H.
 8. The compound ofclaim 3 wherein G¹ is CH₂OH, and G³ is methyl.
 9. The compound of claim2 wherein G¹ is methyl and G³ is H.
 10. The compound of claim 2 whereinG¹ is H and G³ is methyl.
 11. A method of treating a medical conditionrelated to a toxic concentration of iron, wherein the method comprisesadministering to a subject having or suspected of having a medicalcondition related to a toxic concentration of iron, an effect amount ofa compound of formula
 1. 12. The method of claim 11 wherein the medicalcondition related to a toxic concentration of iron is selected from thegroup consisting of cancer, pulmonary disease, progressive kidneydisease and Friedreich's ataxia.